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i am corn holeo i need tipi for me bung hole
{{Otheruses4|the mineral|the gemstone|Diamond (gemstone)|other uses, including the shape <big>[[◊]]</big>}}
{{featured article}}
{{Infobox mineral
|name = Diamond
|category = Native Minerals
|boxwidth =
|boxbgcolor = #7da7d9
|image = Brillanten.jpg
|alt = Seven clear faceted gems, six small stones of similar size and a large one.
|caption = A scattering of round-brilliant cut diamonds shows off the many reflecting facets.
|formula = [[Carbon|C]]
|molweight = {{val|12.01|ul=g/mol}}
|color = Typically yellow, brown or gray to colorless. Less often blue, green, black, translucent white, pink, violet, orange, purple and red.
|habit = [[Octahedral]]
|system = Isometric-Hexoctahedral ([[Cubic crystal system|Cubic]])
|twinning =
|cleavage = 111 (perfect in four directions)
|fracture = [[Conchoidal fracture|Conchoidal]] (shell-like)
|mohs = 10
|luster = [[Lustre_(mineralogy)#Adamantine_lustre|Adamantine]]
|polish = Adamantine
|refractive = 2.418 (at 500 nm)
|opticalprop = Singly Refractive
|birefringence = None
|dispersion = 0.044
|pleochroism = None
|streak = colorless
|gravity = {{val|3.52|0.01}}
|density = 3.5–{{val|3.53|ul=g/cm3}}
hardness =10(hardest mineral or gem)
|[[Transparency (optics)|diaphaneity]] = [[Transparency (optics)|Transparent]] to subtransparent to translucent
|references = <ref name=mindat>{{cite web|publisher=Mindat|title=Diamond|url=http://www.mindat.org/min-1282.html|accessdate=2009-07-07}}</ref><ref name=webmin>{{cite web|publisher=WebMineral|title=Diamond|url=http://webmineral.com/data/Diamond.shtml|accessdate=2009-07-07}}</ref>}}

In [[mineralogy]], '''diamond''' (from the ancient [[Greek language|Greek]] adámas, meaning "proper" or "unalterable") is an [[Allotropes of carbon|allotrope of carbon]], where the [[carbon]] atoms are arranged in a variation of the [[face-centered cubic]] crystal structure called a [[diamond lattice]]. Diamond is the second most stable form of carbon, after [[graphite]]; however, the conversion rate from diamond to graphite is negligible at [[Standard conditions for temperature and pressure|ambient conditions]]. Diamond is specifically renowned as a material with superlative physical qualities, most of which originate from the strong [[covalent bond]]ing between its atoms. In particular, diamond has the highest [[Hardness#Scratch hardness|hardness]] and [[thermal conductivity]] of any bulk material synthesized so far. Those properties determine the major industrial application of diamond in cutting and polishing tools.

Diamond has remarkable optical characteristics. Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as [[boron]] and [[nitrogen]]. Combined with the wide transparency, this results in clear, colorless appearance of most natural diamonds. Small amounts of defects or impurities (about one per million of lattice atoms) color diamond blue (boron), yellow (nitrogen), brown ([[Dislocation|lattice defects]]), green, purple, pink, orange or red. Diamond also has relatively high [[optical dispersion]], that is ability to disperse light of different colors, which results in its characteristic [[luster (mineralogy)|luster]]. Excellent optical and mechanical properties, combined with efficient marketing, make diamond the most popular [[gemstone]].

Most natural diamonds are formed at high-pressure high-temperature conditions existing at depths of {{convert|140|to|190|sp=us|km}} in the Earth [[Mantle (geology)|mantle]]. Carbon-containing minerals provide the carbon source, and the growth occurs over periods from 1&nbsp;billion to 3.3&nbsp;billion years, which respectively corresponds to roughly 25% and 75% of the [[age of the Earth]]. Diamonds are brought close to the Earth surface through deep volcanic eruptions by a [[magma]], which cools into [[igneous rock]]s known as [[kimberlite]]s and [[lamproite]]s. Diamonds can also be produced synthetically in a [[Synthetic diamond#High pressure, high temperature|high-pressure high-temperature]] process which approximately simulates the conditions in the Earth mantle. An alternative, and completely different growth technique is [[chemical vapor deposition]]. Several non-diamond materials, which include [[cubic zirconia]] and [[silicon carbide]] and are often called [[diamond simulants]], resemble diamond in appearance and many properties. Special [[Gemology|gemological]] techniques have been specially developed to distinguish natural and [[synthetic diamond]]s and diamond simulants.

==History==
{{See also|Diamond (gemstone)}}

The name ''diamond'' is derived from the [[Greek language|ancient Greek]] ''ἀδάμας'' ''(adámas''), "proper", "unalterable", "unbreakable, untamed", from [[:wiktionary:ἀ-|ἀ-]] (a-), "un-" + ''δαμάω'' (''damáō''), "I overpower, I tame".<ref>
{{cite web
|last=Liddell |first=H.G. |last2=Scott |first2=R.
|title=Adamas
|work=A Greek-English Lexicon
|url=http://www.perseus.tufts.edu/cgi-bin/ptext?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3D%231145
|publisher=[[Perseus Project]]
}}</ref> However, diamonds are thought to have been first recognized and mined in India, where significant [[alluvial deposit]]s of the stone could then be found many centuries ago along the rivers [[Penner River|Penner]], [[Krishna River|Krishna]] and [[Godavari River|Godavari]]. Diamonds have been known in India for at least 3,000 years but most likely 6,000 years.<ref name=hershey>
{{cite book
|url=http://books.google.com/books?id=35eij1e1al8C&pg=PA23
|last=Hershey |first=W.
|title=The Book of Diamonds
|publisher=Hearthside Press
|location=New York
|year=1940
|pages=22–28
|isbn=1417977159
}}</ref>

Diamonds have been treasured as gemstones since their use as [[icon|religious icons]] in [[Kingdoms of Ancient India|ancient India]]. Their usage in engraving tools also dates to early [[History of the world|human history]].<ref>
{{cite book
|author=[[Pliny the Elder]]
|title=Natural History: A Selection
|publisher=[[Penguin Books]]
|page=371
|year=2004
|isbn=0140444130
}}</ref><ref name=ancient_China>
{{cite news
|title=Chinese made first use of diamond
|url=http://news.bbc.co.uk/2/hi/science/nature/4555235.stm
|publisher=[[BBC News]]
|date=2005-05-17
|accessdate=2007-03-21
}}</ref> Popularity of diamonds has risen since the 19th century because of increased supply, improved cutting and polishing techniques, growth in the world economy, and innovative and successful advertising campaigns.<ref name=sell/>

In 1813, [[Humphry Davy]] used a lens to concentrate the rays of the sun on a diamond in an atmosphere of [[oxygen]], and showed that the only product of the combustion was [[carbon dioxide]], proving that diamond is composed of carbon. Later, he showed that in an atmosphere devoid of oxygen, diamond is converted to graphite.<ref>
{{cite book
|last=Thomas |first=J.M.L.
|title=Michael Faraday and the Royal Institution: The Genius of Man and Place
|publisher=Adam Hilger
|location=Bristol
|year=1991
|page=19
|isbn=0-7503-0145-7
}}</ref>

The most familiar usage of diamonds today is as gemstones used for [[adornment]], a usage which dates back into antiquity. The [[Dispersion (optics)|dispersion]] of white light into [[spectral color]]s is the primary gemological characteristic of gem diamonds. In the twentieth century, experts in the field of [[gemology]] have developed methods of grading diamonds and other gemstones based on the characteristics most important to their value as a gem. Four characteristics, known informally as the ''four Cs'', are now commonly used as the basic descriptors of diamonds: these are ''carat'', ''cut'', ''color'', and ''clarity''.<ref>{{cite book|url=http://books.google.com/books?id=DIWEi5Hg93gC&pg=PA42|page=42|author=Hesse, R. W.|title=Jewelrymaking through history| publisher=Greenwood Publishing Group| year= 2007|isbn=0313335079}}</ref>

==Material properties==
{{Main|Material properties of diamond|Crystallographic defects in diamond}}
[[Image:Diamond and graphite2.jpg|thumb|alt=Four panels. First, seven clear faceted gems, six small and a large one. Second, black material with uneven surface. Third, three parallel atomic sheets, each resembling a chicken wire hedge. Fourth, a boxed atomic structure containing tetrahedrally arranged balls connected by 0.15 nm bonds.|Diamond and graphite are two [[allotrope]]s of [[carbon]]: pure forms of the same element that differ in structure.]]

A diamond is a [[transparency (optics)|transparent]] [[crystal]] of [[Tetrahedral-octahedral honeycomb|tetrahedrally]] bonded carbon atoms ([[Orbital hybridisation|sp<sup>3</sup>]]) that crystallizes into the [[Diamond cubic|diamond lattice]] which is a variation of the [[face centered cubic]] structure. Diamonds have been adapted for many uses because of the material's exceptional physical characteristics. Most notable are its extreme hardness and [[thermal conductivity]] (900–{{val|2320|u=W·m{{sup|−1}}·K{{sup|−1}}}}),<ref name=PNU>
{{cite journal
|last=Wei |first=L. |coauthors=''et al.''
|title=Thermal conductivity of isotopically modified single crystal diamond
|journal=Physical Review Letters
|volume=70 |page=3764
|year=1993
|doi =10.1103/PhysRevLett.70.3764
}}</ref> as well as wide [[bandgap]] and high optical [[dispersion (optics)|dispersion]].<ref name=walker/> Above {{val|1700|ul=degC}} ({{val|1973|ul=K}} / {{val|3583|ul=degF}}) in [[vacuum]] or oxygen-free atmosphere, diamond converts to graphite; in air, transformation starts at ~{{val|700|u=degC}}.<ref>{{cite journal| doi =10.1016/S0925-9635(01)00673-2| title =The oxidation of (100) textured diamond| year =2002| author =John, P| journal =Diamond and Related Materials| volume =11| page=861}}</ref> Naturally occurring diamonds have a density ranging from 3.15–{{val|3.53|u=g/cm3}}, with pure diamond close to {{val|3.52|u=g/cm3}}.<ref name=mindat/> Despite the hardness of diamonds, the chemical bonds that hold the carbon atoms in diamonds together are actually weaker than those that hold together the other form of pure carbon, graphite. The difference is that in diamonds, the bonds form an inflexible three-dimensional lattice. In graphite, the atoms are tightly bonded into sheets, which can slide easily however.<ref name=Pop>{{cite journal
|last=Gray |first=Theodore
|title=Gone in a Flash
|journal=Popular Science
|page=70
|month=September
|year=2009
}}</ref>

===Hardness===
Diamond is the hardest natural material known, where hardness is defined as resistance to scratching and is graded between 1 (softest) and 10 (hardest) using the [[Mohs scale of mineral hardness]]. Diamond has a hardness of 10 (hardest) on this scale.<ref name=read>{{cite book|url=http://books.google.com/books?id=t-OQO3Wk-JsC&pg=PA49|pages=49–50|title=Gemmology|author=Read, P. G.|publisher=Butterworth-Heinemann|year= 2005|isbn=0750664495}}</ref> Diamond's hardness has been known since antiquity, and is the source of its name.

The diamond hardness depends on its purity, crystalline perfection and orientation: hardness is higher for flawless, pure crystals oriented to the [[Miller_index#Case_of_the_cubic_structures|<111>]] direction (along the longest diagonal of the cubic diamond lattice).<ref>{{cite book|pages=142–147|url=http://books.google.com/books?id=jtC1mUFZfQcC&pg=PA143|title=Properties, Growth and Applications of Diamond|author=Neves, A. J. and Nazaré, M. H.|publisher=[[Institution of Engineering and Technology]]|year= 2001|isbn=0852967853}}</ref> Therefore, whereas it might be possible to scratch some diamonds with other materials, such as [[boron nitride]], the hardest diamonds can only be scratched by other diamonds. In particular, [[Aggregated diamond nanorod|nanocrystalline diamond aggregates]] were measured to be harder than any large single crystal diamond. Those aggregates are produced by high-pressure high-temperature treatment of [[graphite]] or [[fullerite]] (C<sub>60</sub>).<ref name=blank>
{{cite journal
|last=Blank |first=V. |coauthors=''et al.''
|title=Ultrahard and superhard phases of fullerite C<sub>60</sub>: comparison with diamond on hardness and wear
|url=http://www.nanoscan.info/files/article_03.pdf
|journal=Diamond and Related Materials
|volume=7 |issue=2–5|page=427–431
|year=1998
|doi=10.1016/S0925-9635(97)00232-X
}}</ref>

The hardness of diamonds contributes to its suitability as a gemstone. Because it can only be scratched by other diamonds, it maintains its polish extremely well. Unlike many other gems, it is well-suited to daily wear because of its resistance to scratching—perhaps contributing to its popularity as the preferred gem in [[engagement ring|engagement]] or [[wedding ring]]s, which are often worn every day.

The hardest natural diamonds mostly originate from the Copeton and Bingara fields located in the [[New England (Australia)|New England]] area in [[New South Wales]], Australia. These diamonds are generally small, perfect to semiperfect octahedra, and are used to polish other diamonds. Their hardness is associated with the [[crystal growth]] form, which is single-stage crystal growth. Most other diamonds show more evidence of multiple growth stages, which produce inclusions, flaws, and defect planes in the crystal lattice, all of which affect their hardness. It is possible to treat regular diamonds under a combination of high pressure and high temperature to produce diamonds that are harder than the diamonds used in hardness gauges.<ref name="Smithsonian">
{{cite journal
|last=Boser |first=U.
|title=Diamonds on Demand
|url=http://www.smithsonianmag.com/science-nature/diamonds-on-demand.html
|journal=[[Smithsonian (magazine)|Smithsonian]]
|volume=39 |issue=3 |pages=52–59
|year=2008
|doi=
}}</ref>

Somewhat related to hardness is another mechanical property ''toughness'', which is a material's ability to resist breakage from forceful impact. The [[toughness]] of natural diamond has been measured as {{val|2.0|u=[[Megapascal|MPa]]·[[meter|m]]<sup>1/2</sup>}},<ref>
{{cite book
|last=Weber |first=M.J.
|title=Handbook of optical materials
|url=http://books.google.de/books?id=6VpQDoef05wC
|page=119
|publisher=[[CRC Press]]
|year=2002
|isbn=0849335124
}}</ref> and the critical stress intensity factor is {{val|3.4|u=[[Meganewton|MN]]·[[meter|m]]<sup>−3/2</sup>}}.<ref>
{{cite journal
|last=Field |first=J.E.
|title=Strength and Fracture Properties of Diamond
|journal=[[Philosophical Magazine A]]
|volume=43 |issue=3 |pages=595–618
|publisher=[[Taylor & Francis]]
|year=1981
|doi=10.1080/01418618108240397
}}</ref> Those values are good compared to other gemstones, but poor compared to most engineering materials. As with any material, the macroscopic geometry of a diamond contributes to its resistance to breakage. Diamond has a cleavage plane and is therefore more fragile in some orientations than others. [[Diamond cutting|Diamond cutters]] use this attribute to cleave some stones, prior to faceting.<ref name=harlow/>

===Electrical conductivity===
Other specialized applications also exist or are being developed, including use as [[semiconductor]]s: some blue diamonds are natural semiconductors, in contrast to most other diamonds, which are excellent electrical [[Electrical insulation|insulator]]s.<ref name="boron"/> The conductivity and blue color originate from the boron impurity. Boron substitutes for carbon atoms in the diamond lattice, donating a hole into the valence band.<ref name="boron">
{{cite journal
|last=Collins |first=A.T.
|title=The Optical and Electronic Properties of Semiconducting Diamond
|journal=[[Philosophical Transactions of the Royal Society A]]
|volume=342 |pages=233–244
|year=1993
|doi=10.1098/rsta.1993.0017
}}</ref>

Substantial conductivity is commonly observed in nominally undoped diamond grown by [[Chemical vapor deposition of diamond|chemical vapor deposition]]. This conductivity is associated with hydrogen-related species adsorbed at the surface, and it can be removed by annealing or other surface treatments.<ref name="Landstrass">
{{cite journal
|last=Landstrass |first=M.I. |last2=Ravi |first2=K.V.
|title=Resistivity of chemical vapor deposited diamond films
|journal=[[Applied Physics Letters]]
|volume=55 |pages=975–977
|year=1989
|doi=10.1063/1.101694
}}</ref><ref>
{{cite journal
|last=Zhang |first=W. |last2=Ristein |first2=J. |last3=Ley |first3=L.
|title=Hydrogen-terminated diamond electrodes. II. Redox activity
|journal=[[Physical Review E]]
|volume=78 |page=041603
|year=2008
|doi=10.1103/PhysRevE.78.041603
}}</ref>

===Color===
{{Main|Diamond color}}
[[Image:National Museum of Natural History Gold Colored Diamonds.JPG|alt=A museum display of jewelry items. Three brooches each consist of a large brown central gem surrounded by many clear small stones. A necklace has a large brown gem at its bottom and its string is all covered with small clear gems. A cluster-shaped decoration contains many brown gems.|300px|thumb|Brown colored diamonds at the [[National Museum of Natural History]] in [[Washington, D.C]]]]

Diamond has a wide bandgap of {{val|5.5|ul=eV}} corresponding to the deep [[ultraviolet]] wavelength of 225 nanometers. This means pure diamond should transmit visible light and appear as a clear colorless crystal. Colors in diamond originate from lattice defects and impurities. The diamond crystal lattice is exceptionally strong and only atoms of nitrogen, boron and hydrogen can be introduced into diamond during the growth at significant concentrations (up to atomic percents). Transition metals Ni and Co, which are commonly used for growth of synthetic diamond by the high-pressure high-temperature techniques, have been detected in diamond as individual atoms, however the maximum concentration is 0.01% for Ni<ref>
{{cite journal
|last=Collins |first=A.T. |coauthors=''et al.''
|title=Correlation between optical absorption and EPR in high-pressure diamond grown from a nickel solvent catalyst
|journal=Diamond and Related Materials
|volume=7 |pages=333–338
|year=1998
|doi=10.1016/S0925-9635(97)00270-7
}}</ref> and even much less for Co. Note however, that virtually any element can be introduced in diamond by ion implantation.<ref name=zaitsev>
{{cite journal|doi=10.1103/PhysRevB.61.12909|title=Vibronic spectra of impurity-related optical centers in diamond|year=2000|author=Zaitsev, A. M.|journal=Physical Review B|volume=61|pages=12909}}</ref>

Nitrogen is by far the most common impurity found in gem diamonds. Nitrogen is responsible for the yellow and brown in diamonds. Boron is responsible for the gray blue colors.<ref name=walker>
{{cite journal
|last=Walker |first=J.
|title=Optical absorption and luminescence in diamond
|journal=Reports on Progress in Physics
|volume=42 |page=1605–1659
|year=1979
|doi=10.1088/0034-4885/42/10/001
}}</ref> Color in diamond has two additional sources: irradiation (usually by alpha particles), that causes the color in green diamonds; and physical deformation of the diamond crystal known as plastic deformation. Plastic deformation is the cause of color in some brown<ref>
{{cite journal
|last=Hounsome |first=L.S. |coauthors=''et al.''
|title=Origin of brown coloration in diamond
|journal=[[Physical Review B]]
|volume=73 |pages=125203
|year=2006
|doi=10.1103/PhysRevB.73.125203
}}</ref> and perhaps pink and red diamonds.<ref>
{{cite book
|last=Wise |first=R.W.
|title=Secrets Of The Gem Trade, The Connoisseur's Guide To Precious Gemstones
|publisher=Brunswick House Press
|pages=223–224
|year=2001
|isbn=9780972822381
}}</ref> In order of rarity, colorless diamond, by far the most common, is followed by yellow and brown, by far the most common colors, then by blue, green, black, translucent white, pink, violet, orange, purple, and the rarest, red.<ref name=harlow/> "Black", or [[Carbonado]], diamonds are not truly black, but rather contain numerous dark inclusions that give the gems their dark appearance. Colored diamonds contain impurities or structural defects that cause the coloration, while pure or nearly pure diamonds are transparent and colorless. Most diamond impurities replace a carbon atom in the [[crystal lattice]], known as a [[carbon flaw]]. The most common impurity, nitrogen, causes a slight to intense yellow coloration depending upon the type and concentration of nitrogen present.<ref name=harlow/> The [[Gemological Institute of America]] (GIA) classifies low saturation yellow and brown diamonds as diamonds in the ''normal color range'', and applies a grading scale from "D" (colorless) to "Z" (light yellow). Diamonds of a different color, such as blue, are called ''fancy colored'' diamonds, and fall under a different grading scale.<ref name=harlow/>

In 2008, the [[Wittelsbach Diamond]], a {{convert|35.56|carat|g}} blue diamond once belonging to the King of Spain, fetched over US$24 million at a Christie's auction.<ref>
{{cite news
|last=Khan |first=U
|title=Blue-grey diamond belonging to King of Spain has sold for record 16.3 GBP
|url=http://www.telegraph.co.uk/culture/3703861/Blue-grey-diamond-belonging-to-King-of-Spain-has-sold-for-record-16.3m.html
|publisher=[[The Daily Telegraph|The Telegraph]]
}}</ref> In 2009 a {{convert|7.03|carat|g}} blue diamond fetched the highest price per-carat ever paid for a diamond when it was sold at auction for 10.5 million Swiss francs (6.97 million Euro or US$9.5 million at the time) which is in excess of US$1.3 million per carat.<ref>
{{cite news
|last=Nebehay |first=S.
|title=Rare blue diamond sells for record $9.5 million
|url=http://www.reuters.com/article/artsNews/idUSTRE54B6O020090512
|publisher=[[Reuters]]
|date=2009-05-12
|accessdate=2009-05-13
}}</ref>

===Identification===
Diamonds can be identified by their high thermal conductivity. Their high [[refractive index]] is also indicative, but other materials have similar refractivity. Diamonds do cut glass, but this does not positively identify a diamond because other materials, such as quartz, also lie above glass on the [[Mohs scale]] and can also cut glass. Diamonds can scratch other diamonds, but this can result in damage to one or both stones. Hardness tests are infrequently used in practical gemology because of their potentially destructive nature.<ref name=read/>
The extreme hardness and high value of diamond means that gems are typically polished slowly using painstaking traditional techniques and greater attention to detail than is the case with most other gemstones;<ref>{{cite book|url=http://books.google.com/books?id=fNJQok6N9_MC&pg=PA7|page=7|title=The diamond makers|author=Hazen, R. M|publisher=Cambridge University Press|year=1999|isbn=0521654742}}</ref> these tend to result in extremely flat, highly polished facets with exceptionally sharp facet edges. Diamonds also possess an extremely high refractive index and fairly high dispersion. Taken together, these factors affect the overall appearance of a polished diamond and most diamantaires still rely upon skilled use of a [[loupe]] (magnifying glass) to identify diamonds 'by eye'.<ref>{{cite book|url=http://books.google.com/books?id=Jm3FwBiHaI4C&pg=PA37|pages=34–37|title=Synthetic, Imitation and Treated Gemstones|author=O'Donoghue, M.|publisher=Gulf Professional Publishing|year= 1997|isbn=0750631732}}</ref>

==Natural history==
The formation of natural diamond requires very specific conditions—exposure of carbon-bearing materials to high pressure, ranging approximately between 45 and 60 [[Bar (unit)|kilobar]]s, but at a comparatively low temperature range between approximately 1650–2370 °F (900–1300 °C). These conditions are met in two places on Earth; in the [[Lithosphere|lithospheric mantle]] below relatively stable [[continental plate]]s, and at the site of a meteorite strike.<ref name=core>{{cite book|title=The Mantle and Core|author= Carlson, R.W.|url=http://books.google.com/books?id=1clZ4ABsfoAC&pg=PA248|page=248|publisher =Elsevier|year= 2005|isbn=0080448488}}</ref>

===Formation in cratons===
The conditions for diamond formation to happen in the lithospheric mantle occur at considerable depth corresponding to the aforementioned requirements of temperature and pressure. These depths are estimated between 140 and 190&nbsp;km though occasionally diamonds have crystallized at depths about 300&nbsp;km as well.<ref name="AMNH"/> The rate at which [[geothermal gradient|temperature changes with increasing depth]] into the Earth varies greatly in different parts of the Earth. In particular, under oceanic plates the temperature rises more quickly with depth, beyond the range required for diamond formation at the depth required. The correct combination of temperature and pressure is only found in the thick, ancient, and stable parts of [[continental plate]]s where regions of lithosphere known as ''[[craton]]s'' exist. Long residence in the cratonic lithosphere allows diamond crystals to grow larger.<ref name="AMNH">
{{cite book
|last=Erlich |first=E.I. |last2=Dan Hausel |first2=W.
|title=Diamond Deposits
|url=http://books.google.com/books?id=068-M3xrDSQC&printsec=frontcover
|pages=74–94
|publisher=Society for Mining, Metallurgy, and Exploration
|year=2002
|isbn=0873352130
}}</ref>

[[Image:Rough diamond.jpg|left|thumb|250px|alt=A clear octahedral stone protrudes from a black rock.|The slightly misshapen [[octahedral]] shape of this rough diamond crystal in matrix is typical of the mineral. Its lustrous faces also indicate that this crystal is from a primary deposit.]]

Through studies of carbon [[isotope]] ratios (similar to the methodology used in [[carbon dating]], except with the [[stable isotope]]s [[Carbon-12|C-12]] and [[Carbon-13|C-13]]), it has been shown that the carbon found in diamonds comes from both inorganic and organic sources. Some diamonds, known as [[Peridotite|''harzburgitic'']], are formed from inorganic carbon originally found deep in the Earth's [[Mantle (geology)|mantle]]. In contrast, [[eclogite|''eclogitic'']] diamonds contain organic carbon from organic [[detritus]] that has been pushed down from the surface of the Earth's [[crust (geology)|crust]] through [[subduction]] (see [[plate tectonics]]) before transforming into diamond. These two different source of carbons have measurably different <sup>13</sup>C:<sup>12</sup>C ratios. Diamonds that have come to the Earth's surface are generally quite old, ranging from under 1&nbsp;[[1000000000 (number)|billion]] to 3.3&nbsp;billion years old. This is 22% to 73% of the [[age of the Earth]].<ref name="AMNH"/>

Diamonds occur most often as [[euhedral]] or rounded [[octahedron|octahedra]] and [[Crystal twinning|twinned]] octahedra known as ''macles''. As diamond's crystal structure has a cubic arrangement of the atoms, they have many [[facet]]s that belong to a [[Cube (geometry)|cube]], [[octahedron]], [[rhombicosidodecahedron]], [[tetrakis hexahedron]] or [[disdyakis dodecahedron]]. The crystals can have rounded off and unexpressive edges and can be elongated. Sometimes they are found grown together or form double "twinned" crystals at the surfaces of the octahedron. These different shapes and habits of the diamonds result from differing external circumstances. Diamonds (especially those with rounded crystal faces) are commonly found coated in ''nyf'', an opaque gum-like skin.<ref>
{{cite book
|last=Webster |first=R. |last2=Read |first2=P.G.
|title=Gems: Their sources, descriptions and identification
|edition=5th
|page=17
|publisher=[[Butterworth-Heinemann]] |location=Great Britain
|year=2000
|isbn=0-7506-1674-1
}}</ref>

===Formation in meteorite impact craters===
Diamonds can also form in other natural high-pressure events. Very small diamonds of micrometer and nanometer sizes, known as ''microdiamonds'' or ''nanodiamonds'' respectively, have been found in meteorite [[impact crater]]s. Such impact events create shock zones of high pressure and temperature suitable for diamond formation. Impact-type microdiamonds can be used as an indicator of ancient impact craters.<ref name=core/>

===Extraterrestrial formation===
Not all diamonds found on Earth originated here. A type of diamond called [[carbonado]] diamond that is found in South America and Africa may have been deposited there via an asteroid impact (not formed from the impact) about 3&nbsp;billion years ago. These diamonds may have formed in the intrastellar environment, but as of 2008, there was no scientific consensus on how [[carbonado]] diamonds originated.<ref name=Garai2006>
{{cite journal
|first=J. |last=Garai |last2=Haggerty |first2=S.E. |last3=Rekhi |first3=S. |last4=Chance |first4=M.
|year=2006
|title=Infrared Absorption Investigations Confirm the Extraterrestrial Origin of Carbonado Diamonds
|journal=[[Astrophysical Journal]]
|volume=653 |issue=2 |pages=L153–L156
|doi=10.1086/510451
}}</ref><ref name=Carbonardo>
{{cite web
|title=Diamonds from Outer Space: Geologists Discover Origin of Earth's Mysterious Black Diamonds
|url=http://www.nsf.gov/news/news_summ.jsp?cntn_id=108270&org=NSF
|publisher=[[National Science Foundation]]
|date=2007-01-08
|accessdate=2007-10-28
}}</ref>

[[Presolar grains]] in many meteorites found on Earth contain nanodiamonds of extraterrestrial origin, probably formed in [[supernova]]s. Scientific evidence indicates that [[white dwarf]] stars have a core of crystallized carbon and oxygen nuclei. The largest of these found in the universe so far, [[BPM 37093]], is located {{convert|50|ly|km}} away in the constellation [[Centaurus]]. A news release from the [[Harvard-Smithsonian Center for Astrophysics]] described the {{convert|2500|mi|adj=on}} wide stellar core as a ''diamond''.<ref>
{{cite news
|title=This Valentine's Day, Give The Woman Who Has Everything The Galaxy's Largest Diamond
|url=http://cfa-www.harvard.edu/press/archive/pr0407.html
|publisher=Center for Astrophysics
|date=
|accessdate=2009-05-05
}}</ref> It was referred to as ''Lucy'', after the Beatles song "Lucy in the Sky With Diamonds".<ref name="Smithsonian" /><ref>
{{cite web
|last=Cauchi |first=S.
|title=Biggest Diamond Out of This World
|url=http://www.theage.com.au/articles/2004/02/17/1076779973101.html
|work=[[The Age]]
|date=2004-02-18
|accessdate=2007-11-11
}}</ref>

===Surfacing===
[[Image:VolcanicPipe.jpg|right|thumb|float|220px|alt=Schematic cross section of an underground region 3 km deep and 2 km wide. A red dike stretches across the bottom, and a pipe containing some xenoliths runs from the dike to the surface, varing from red at the bottom to orange-yellow at the top. The pipe's root, at its bottom, is about 1 km long, and its diatreme, above the root, is about 1.5 km long. The pipe's top is a crater, rimmed by a tuff ring and containing washed-back ejecta. The erosion level is almost zero for Orapa, about 1 km for Jagersfontein, and about 1.4 km for Kimberley.|Schematic diagram of a [[volcanic pipe]]]]

Diamond-bearing rock is brought close to the surface through deep-origin volcanic eruptions. The [[magma]] for such a volcano must originate at a depth where diamonds can be formed<ref name="AMNH"/>—{{convert|150|km|mi|abbr=on|lk=off}} or more (three times or more the depth of source magma for most volcanoes). This is a relatively rare occurrence. These typically small surface volcanic craters extend downward in formations known as [[volcanic pipe]]s.<ref name="AMNH"/> The pipes contain material that was transported toward the surface by volcanic action, but was not ejected before the volcanic activity ceased. During eruption these pipes are open to the surface, resulting in open circulation; many [[xenolith]]s of surface rock and even wood and/or fossils are found in volcanic pipes. Diamond-bearing volcanic pipes are closely related to the oldest, coolest regions of [[continental crust]] ([[craton]]s). This is because cratons are very thick, and their [[lithosphere|lithospheric]] mantle extends to great enough depth that diamonds are stable. Not all pipes contain diamonds, and even fewer contain enough diamonds to make mining economically viable.<ref name="AMNH"/>

The magma in volcanic pipes is usually one of two characteristic types, which cool into [[igneous rock]] known as either [[kimberlite]] or [[lamproite]].<ref name="AMNH"/> The magma itself does not contain diamond; instead, it acts as an elevator that carries deep-formed rocks (xenoliths), minerals ([[xenocryst]]s), and fluids upward. These rocks are characteristically rich in [[magnesium]]-bearing [[olivine]], [[pyroxene]], and [[amphibole]] minerals<ref name="AMNH"/> which are often altered to [[serpentine]] by heat and fluids during and after eruption. Certain ''indicator minerals'' typically occur within diamantiferous kimberlites and are used as mineralogical tracers by prospectors, who follow the indicator trail back to the volcanic pipe which may contain diamonds. These minerals are rich in [[chromium]] (Cr) or [[titanium]] (Ti), elements which impart bright colors to the minerals. The most common indicator minerals are chromium [[garnet]]s (usually bright red chromium-[[pyrope]], and occasionally green ugrandite-series garnets), eclogitic garnets, orange titanium-pyrope, red high-chromium [[spinel]]s, dark [[chromite]], bright green chromium-[[diopside]], glassy green [[olivine]], black [[ilmenite|picroilmenite]], and [[magnetite]]. Kimberlite deposits are known as ''blue ground'' for the deeper serpentinized part of the deposits, or as ''yellow ground'' for the near surface [[smectite]] [[clay]] and carbonate [[weathering|weathered]] and [[oxidation|oxidized]] portion.<ref name="AMNH"/>

Once diamonds have been transported to the surface by magma in a volcanic pipe, they may erode out and be distributed over a large area. A volcanic pipe containing diamonds is known as a ''primary source'' of diamonds. ''Secondary sources'' of diamonds include all areas where a significant number of diamonds, eroded out of their kimberlite or lamproite matrix, and accumulated because of water or wind action. These include [[alluvium|alluvial]] deposits and deposits along existing and ancient shorelines, where loose diamonds tend to accumulate because of their approximate size and density. Diamonds have also rarely been found in deposits left behind by glaciers (notably in [[Wisconsin]] and [[Indiana]]); however, in contrast to alluvial deposits, glacial deposits are minor and are therefore not viable commercial sources of diamond.<ref name="AMNH"/>

==Production==
[[Image:Diamond output2.PNG|thumb|right|350px|alt=A world map showing that roughly half of diamonds originate from Africa, and one-third from Australia. The remaining part is mostly due to Russia with minor contribution from Canada and China.|Diamond output in 2005]]
{{See also|List of diamond mines}}

Approximately 130&nbsp;million [[Carat (mass)|carats]] ({{convert|26000|kg|abbr=on}}) of diamonds are mined annually, with a total value of nearly US$9&nbsp;[[1000000000 (number)|billion]], and about {{convert|100000|kg|abbr=on}} are synthesized annually.<ref name=yarnell>
{{cite journal
|last=Yarnell |first=A.
|title=The Many Facets of Man-Made Diamonds
|url=http://pubs.acs.org/cen/coverstory/8205/8205diamonds.html
|journal=[[Chemical and Engineering News]]
|volume=82 |issue=5 |pages=26–31
|year=2004
}}</ref>

Roughly 49% of diamonds originate from central and southern Africa, although significant sources of the mineral have been discovered in Canada, India, Russia, [[Brazil]], and Australia.<ref name=usgs/> They are mined from kimberlite and lamproite volcanic pipes, which can bring diamond crystals, originating from deep within the Earth where high pressures and temperatures enable them to form, to the surface. The mining and distribution of natural diamonds are subjects of frequent controversy such as with concerns over the sale of ''[[conflict diamond]]s'' or ''blood diamonds'' by African [[paramilitary]] groups.<ref name=conflict>
{{cite web
|title=Conflict Diamonds
|url=http://www.un.org/peace/africa/Diamond.html
|publisher=[[United Nations]]
|date=2001-03-21
|accessdate=2009-05-05
}}</ref> The diamond supply chain is controlled by a limited number of powerful businesses, and is also highly concentrated in a small number of locations around the world (see figure).

Only a very small fraction of the diamond ore consists of actual diamonds. The ore is crushed, during which care is required not to destroy larger diamonds, and then sorted by density. Today, diamonds are located in the diamond-rich density fraction with the help of [[X-ray fluorescence]], after which the final sorting steps are done by hand. Before the use of [[X-ray]]s became commonplace,<ref name=x50/> the separation was done with grease belts; diamonds have a stronger tendency to stick to grease than the other minerals in the ore.<ref name=harlow>
{{cite book
|last=Harlow |first=G.E.
|title=The nature of diamonds
|page=223;230-249
|url=http://books.google.com/books?id=_WI86J88ydAC&pg=PA223
|publisher=[[Cambridge University Press]]
|year=1998
|isbn=0521629357
}}</ref>

Historically diamonds were found only in alluvial deposits in [[southern India]].<ref name=Catelle1>
{{cite book
|last=Catelle |first=W.R.
|title=The Diamond
|publisher=John Lane Company
|year=1911
|page=159}}</ref> India led the world in diamond production from the time of their discovery in approximately the 9th century BC<ref name=hershey/><ref name=Ball>
{{cite book
|last=Ball |first=V.
|chapter=Chapter 1
|title=Diamonds, Gold and Coal of India
|page=1
|publisher=Trübner & Co |location=London
|year=1881
}} Ball was a geologist in British service.</ref> to the mid-18th century AD, but the commercial potential of these sources had been exhausted by the late 18th century and at that time India was eclipsed by Brazil where the first non-Indian diamonds were found in 1725.<ref name=hershey/>

Diamond production of primary deposits (kimberlites and lamproites) only started in the 1870s after the discovery of the [[Diamond Fields]] in South Africa.<ref>
{{cite book|title=Encyclopedia of African history|author=Shillington, K.|page=767|url=http://books.google.com/books?id=Ftz_gtO-pngC&pg=PA767|publisher=CRC Press|tear= 2005|isbn=1579584535|year=2005}}
</ref> Production has increased over time and now an accumulated total of 4.5&nbsp;billion carats have been mined since that date.<ref name=giasummer2007>
{{cite journal
|last=Janse |first=A.J.A.
|title=Global Rough Diamond Production Since 1870
|journal=Gems & Gemology
|volume=43 |pages=98–119
|year=2007
|doi=
}}</ref> Twenty percent of that amount has been mined in the last five years, and during the last 10 years, nine new mines have started production; four more are waiting to be opened soon. Most of these mines are located in Canada, Zimbabwe, Angola, and one in Russia.<ref name=giasummer2007/>

In the U.S., diamonds have been found in [[Arkansas]], [[Colorado]], and [[Montana]].<ref name=DGemGLorenz>
{{cite journal
|last=Lorenz |first=V.
|title=Argyle in Western Australia: The world's richest diamantiferous pipe; its past and future
|journal=Gemmologie, Zeitschrift der Deutschen Gemmologischen Gesellschaft
|volume=56 |issue=1–2 |pages=35–40
|year=2007
|doi=
}}</ref><ref name=Montana>
{{cite web
|title=Microscopic diamond found in Montana
|url=http://www.montanastandard.com/articles/2004/10/18/featuresbusiness/hjjfijicjbhdjc.txt
|work=[[The Montana Standard]]
|accessdate=2009-05-05
}}</ref> In 2004, the discovery of a microscopic diamond in the U.S. led to the January 2008 bulk-sampling of [[kimberlite pipes]] in a remote part of [[Montana]].<ref name=Montana/><ref>
{{cite web
|title=Apex Geoscience Completes Bulk Sampling, Submits Samples for Laboratory Testing
|url=http://www.deltamine.com/release2008-01-08.htm
|publisher=[[Delta Consolidated Mining Company|Delta Mining]]
|date=2008
|accessdate=2008-11-03
}}</ref>

Today, most commercially viable diamond deposits are in Russia (mostly in [[Sakha Republic]], for example [[Mir Mine|Mir pipe]] and [[Udachnaya pipe]]), [[Botswana]], Australia (Northern and Western Australia) and the [[Democratic Republic of Congo]].<ref>
{{cite web
|last=Marshall |first=S. |coauthors=Shore, J.
|title=The Diamond Life
|url=http://gnn.tv/videos/2/The_Diamond_Life
|publisher=[[Guerrilla News Network]]
|year=2004
|accessdate=2007-03-21
}}</ref> In 2005, Russia produced almost one-fifth of the global diamond output, reports the [[British Geological Survey]]. Australia boasts the richest diamantiferous pipe with production reaching peak levels of {{convert|42|MT}} per year in the 1990s.<ref name=DGemGLorenz/> There are also commercial deposits being actively mined in the [[Northwest Territories]] of Canada and [[Brazil]].<ref name=usgs/> Diamond prospectors continue to search the globe for diamond-bearing kimberlite and lamproite pipes.

===Controversial sources===
{{seealso|Blood diamond}}
In some of the more politically unstable central African and west African countries, revolutionary groups have taken control of [[List of diamond mines|diamond mines]], using proceeds from diamond sales to finance their operations. Diamonds sold through this process are known as ''conflict diamonds'' or ''blood diamonds''.<ref name=conflict/> Major diamond trading corporations continue to fund and fuel these conflicts by doing business with armed groups. In response to public concerns that their diamond purchases were contributing to war and [[human rights abuses]] in [[central Africa|central]] and [[West Africa|western]] Africa, the [[United Nations]], the diamond industry and diamond-trading nations introduced the [[Kimberley Process]] in 2002.<ref name=kimb>{{cite book|url=http://books.google.com/books?id=hWrEcl2ydzEC&pg=PA305|pages=305-313|title=Resource politics in Sub-Saharan Africa|author=Basedau, M.; Mehler, A|year=2005|publisher=GIGA-Hamburg|isbn=3928049917}}</ref> The Kimberley Process aims to ensure that conflict diamonds do not become intermixed with the diamonds not controlled by such rebel groups. This is done by requiring diamond-producing countries to provide proof that the money they make from selling the diamonds is not used to fund criminal or revolutionary activities. Although the Kimberley Process has been moderately successful in limiting the number of conflict diamonds entering the market, some still find their way in. Conflict diamonds constitute 2–3% of all diamonds traded.<ref>
{{cite web
|title=World Federation of Diamond Bourses (WFDB) and International Diamond Manufacturers Association: Joint Resolution of 19 July 2000
|url=http://books.google.ca/books?id=fnRnyS7I9cYC&pg=PA334&lpg=PA334
|publisher=World Diamond Council
|date=2000-07-19
|accessdate=2006-11-05
}}</ref> Two major flaws still hinder the effectiveness of the Kimberley Process: (1) the relative ease of smuggling diamonds across African borders, and (2) the violent nature of diamond mining in nations that are not in a technical state of war and whose diamonds are therefore considered "clean".<ref name=kimb/>

The Canadian Government has set up a body known as Canadian Diamond Code of Conduct<ref>
{{cite web
|title=Voluntary Code of Conduct For Authenticating Canadian Diamond Claims
|url=http://www.cb-bc.gc.ca/eic/site/cb-bc.nsf/vwapj/Code_EN_Jan_06_FINAL.pdf/$file/Code_EN_Jan_06_FINAL.pdf
|publisher=Canadian Diamond Code Committee
|year=2006
|accessdate=2007-10-30
|format=PDF
}}</ref> to help authenticate Canadian diamonds. This is a stringent tracking system of diamonds and helps protect the "conflict free" label of Canadian diamonds.<ref>
{{cite journal
|last=Kjarsgaard |first=B.A. |last2=Levinson |first2=A.A.
|title=Diamonds in Canada
|journal=Gems and Gemology
|volume=38 |issue=3 |pages=208–238
|year=2002
|doi=
}}</ref>

==Commercial markets==
{{See also|Diamonds as an investment}}
[[Image:Diamond.jpg|framed|alt=A clear faceted gem supported in four clamps attached to a wedding ring|A round [[Brilliant (diamond cut)|brilliant cut]] diamond set in a ring]]

The diamond industry can be separated into two basically distinct categories: one dealing with gem-grade diamonds and another for industrial-grade diamonds. While a large trade in both types of diamonds exists, the two markets act in dramatically different ways.

===Gemstones and their distribution===
{{Main|Diamond (gemstone)}}

A large trade in [[Gemstone|gem]]-grade diamonds exists. Unlike other commodities, such as most precious metals, there is a substantial mark-up in the retail sale of gem diamonds.<ref>{{cite web|accessdate=2009-07-07|url=http://www.photius.com/diamonds/the_diamond_industry.html|title=The Diamond Industry}}</ref> There is a well-established market for resale of polished diamonds (e.g. pawnbroking, auctions, second-hand jewelry stores, diamantaires, bourses, etc.). One hallmark of the trade in gem-quality diamonds is its remarkable concentration: wholesale trade and [[diamond cutting]] is limited to just a few locations; In 2003, 92% of the world's diamonds were cut and polished in [[Surat]], [[India]].<ref>
{{cite news
|last=Adiga |first=A.
|title=Uncommon Brilliance
|url=http://www.time.com/time/magazine/article/0,9171,501040419-610100,00.html
|work=[[Time (magazine)|Time]]
|date=2004-04-12
|accessdate=2008-11-03
}}</ref> Other important centers of diamond cutting and trading are [[Antwerp]], where the [[International Gemological Institute]] is based, London, New York City, [[Tel Aviv]], and Amsterdam. A single company—[[De Beers]]—controls a significant proportion of the trade in diamonds.<ref name=debeers>{{cite book|url=http://books.google.com/books?id=xoztFMavGCcC&pg=PA305|page=305|title=Principles of microeconomics|author=Mankiw, N. G|publisher=Elsevier|year=1998|isbn=0030245028|quote=A classic example of monpoly that arises fron ownership of a key resource is DeBeers ... which controls about 80 percent of the world's production of diamonds}}</ref> They are based in [[Johannesburg]], South Africa and London, England. One contributory factor is the geological nature of diamond deposits: several large primary kimberlite-pipe mines each account for significant portions of market share (such as the [[Jwaneng diamond mine|Jwaneng mine]] in Botswana, which is a single large pit operated by De Beers that can produce between 12.5 to 15 million carats of diamonds per year<ref>
{{cite web
|title=Jwaneng
|url=http://www.debeersgroup.com/Exploration-and-mining/Mining-operations/Jwaneng/
|publisher=[[De Beers]]
|accessdate=2009-04-26
}}</ref>), whereas secondary alluvial diamond deposits tend to be fragmented amongst many different operators because they can be dispersed over many hundreds of square kilometers (e.g., alluvial deposits in Brazil).

The production and distribution of diamonds is largely consolidated in the hands of a few key players, and concentrated in traditional diamond trading centers. The most important being Antwerp, where 80% of all rough diamonds, 50% of all cut diamonds and more than 50% of all rough, cut and industrial diamonds combined are handled.<ref name=india>
{{cite book
|last=Tichotsky |first=J.
|title=Russia's Diamond Colony: The Republic of Sakha
|url=http://books.google.com/books?id=F7N4G_wxkUYC
|page=254
|publisher=[[Routledge]]
|year=2000
|isbn=9057024209
}}</ref> This makes Antwerp a de facto "world diamond capital". Another important diamond center is New York City, where almost 80% of the world's diamonds are sold, including auction sales.<ref name=india/> The DeBeers company, as the world's largest diamond miner holds a dominant position in the industry, and has done so since soon after its founding in 1888 by the British imperialist [[Cecil Rhodes]]. De Beers owns or controls a significant portion of the world's rough diamond production facilities (mines) and [[Distribution (business)|distribution channels]] for gem-quality diamonds. The Diamond Trading Company (DTC) is a subsidiary of De Beers and markets rough diamonds from De Beers-operated mines. De Beers and its subsidiaries own mines that produce some 40% of annual world diamond production. For most of the 20th century over 80% of the world's rough diamonds passed through De Beers,<ref>
{{cite web|url=http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:32003D0079:EN:HTML
|title=Commission Decision of 25 July 2001 declaring a concentration to be compatible with the common market and the EEA Agreement|work=Case No COMP/M.2333 – De Beers/LVMH |publisher=[[EUR-Lex]]|year=2003}}</ref> but in the period 2001–2009 the figure has decreased to around 45%.<ref>
{{cite journal
|title=Business: Changing facets; Diamonds
|url=http://pages.stern.nyu.edu/~lwhite/f&m.assignments.2008/f&m.presentationmaterials/DeBeers/Economist%20Feb-24-2007.pdf
|journal=[[The Economist]] |volume=382 |issue=8517 |page=68 |year=2007}}</ref> De Beers sold off the vast majority its diamond stockpile in the late 1990s – early 2000s<ref>{{cite web
|title=The Elusive Sparcle
|url=http://www.gjepc.org/solitaire/magazines/Aug05_Sep05/aug05_sep05.aspx?inclpage=Specials&section_id=3
|publisher=The Gem & Jewellery Export Promotion Council
|accessdate=2009-04-26
}}</ref> and the remainder largely represents working stock (diamonds that are being sorted before sale).<ref>
{{cite news
|last=Even-Zohar |first=C.
|title=Crisis Mitigation at De Beers
|url=http://www.namakwadiamonds.co.za/nd/uploads/wysiwyg/documents/081106_DIB.pdf
|publisher=DIB online
|date=2008-11-06
|accessdate=2009-04-26
|format=PDF
}}</ref> This was well documented in the press<ref>
{{ cite web
|last=Even-Zohar |first=C.
|title=De Beers to Halve Diamond Stockpile
|url=http://www.allbusiness.com/retail-trade/apparel-accessory-stores-womens-specialty/4224156-1.html
|publisher=National Jeweler
|date=1999-11-03
|accessdate=2009-04-26
}}</ref> but remains little known to the general public.

As a part of reducing its influence, De Beers withdrew from purchasing diamonds on the open market in 1999 and ceased, at the end of 2008, purchasing Russian diamonds mined by the largest Russian diamond company [[Alrosa]].<ref>
{{cite web
|title=Judgment of the Court of First Instance of 11 July 2007 – Alrosa v Commission
|url=http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:C:2007:199:0037:01:EN:HTML
|publiser=[[EUR-Lex]]
|date=2007
|accessdate=2009-04-26
}}</ref> Alrosa however had to suspend their sales in October 2008 due to the [[2000s energy crisis|global energy crisis]] and is expected to resume them in autumn 2009.<ref>
{{cite web
|title=Diamond producer Alrosa to resume market diamond sales in May
|url=http://en.rian.ru/business/20090506/121458087.html
|publisher=[[RIA Novosti]]
|date=2009-05-06
|accessdate=2009-05-25
}}</ref> Apart from Alrosa, other important diamond mining companies include [[BHP Billiton]], which is the world's largest mining company;<ref>{{cite news| url =http://www.abc.net.au/news/stories/2007/08/22/2012367.htm| title = Another record profit for BHP
|publisher = ABC News|date = 2007-08-22|accessdate = 2007-08-23}}</ref> [[Rio Tinto Group]], the owner of Argyle (100%), [[Diavik Diamond Mine|Diavik]] (60%), and [[Murowa diamond mine|Murowa]] (78%) diamond mines;<ref name="RTCompanies">{{cite web| title = Our Companies| work = Rio Tinto web site| publisher = Rio Tinto| url = http://www.riotinto.com/whatweproduce/218_our_companies.asp| accessdate = 2009-03-05}}</ref> and [[Petra Diamonds]], the owner of several major diamond mines in Africa.

Further down the supply chain, members of The [[World Federation of Diamond Bourses]] (WFDB) act as a medium for wholesale diamond exchange, trading both polished and rough diamonds. The WFDB consists of independent diamond bourses in major cutting centers such as Tel Aviv, Antwerp, Johannesburg and other cities across the USA, Europe and Asia.<ref name=harlow/> In 2000, the WFDB and The International Diamond Manufacturers Association established the [[World Diamond Council]] to prevent the trading of diamonds used to fund war and inhumane acts. WFDB's additional activities include sponsoring the [[World Diamond Congress]] every two years, as well as the establishment of the ''[[International Diamond Council]]'' (IDC) to oversee diamond grading.

Once purchased by Sightholders (which is a trademark term referring to the companies that have a three-year supply contract with DTC), diamonds are cut and polished in preparation for sale as gemstones ('industrial' stones are regarded as a by-product of the gemstone market; they are used for abrasives).<ref name=polish>{{cite book|url=http://books.google.com/books?id=fkBJ0HL34WsC&pg=PA297|pages=297–299|title=Africa's silk road|author=Broadman, H. G.; Isik, G|publisher=World Bank Publications|year=2007|isbn=0821368354}}</ref> The cutting and polishing of rough diamonds is a specialized skill that is concentrated in a limited number of locations worldwide.<ref name=polish/> Traditional diamond cutting centers are Antwerp, [[Amsterdam]], [[Johannesburg]], New York City, and [[Tel Aviv]]. Recently, diamond cutting centers have been established in China, India, [[Thailand]], Namibia and Botswana.<ref name=polish/> Cutting centers with lower cost of labor, notably [[Surat]] in [[Gujarat|Gujarat, India]], handle a larger number of smaller carat diamonds, while smaller quantities of larger or more valuable diamonds are more likely to be handled in Europe or North America. The recent expansion of this industry in India, employing low cost labor, has allowed smaller diamonds to be prepared as gems in greater quantities than was previously economically feasible.<ref name=india/>

Diamonds which have been prepared as gemstones are sold on diamond exchanges called ''bourses''. There are 26 registered diamond bourses in the world.<ref>
{{cite web
|title=Bourse listing
|url=http://www.worldfed.com/website/boursedirectory.html
|publisher=World Federation of Diamond Bourses
|accessdate=2007-04-04
}}</ref> Bourses are the final tightly controlled step in the diamond supply chain; wholesalers and even retailers are able to buy relatively small lots of diamonds at the bourses, after which they are prepared for final sale to the consumer. Diamonds can be sold already set in jewelry, or sold unset ("loose"). According to the [[Rio Tinto Group]], in 2002 the diamonds produced and released to the market were valued at US$9&nbsp;billion as rough diamonds, US$14&nbsp;billion after being cut and polished, US$28&nbsp;billion in wholesale diamond jewelry, and US$57&nbsp;billion in retail sales.<ref>
{{cite web
|title=North America Diamond Sales Show No Sign of Slowing
|url=http://www.awdiamonds.com/article-8.html
|publisher=A&W diamonds
|accessdate=2009-05-05
}}</ref>

====Marketing====
The image of diamond as a valuable commodity has been preserved through clever marketing campaigns. In particular, the [[De Beers#Marketing|De Beers diamond advertising campaign]] is acknowledged as one of the most successful and innovative campaigns in history. [[N. W. Ayer & Son]], the advertising firm retained by De Beers in the mid-20th century, succeeded in reviving the American diamond market and opened up new markets, even in countries where no diamond tradition had existed before. N. W. Ayer's multifaceted marketing campaign included [[product placement]], advertising the diamond itself rather than the De Beers brand, and building associations with celebrities and royalty. This coordinated campaign has lasted decades and continues today; it is perhaps best captured by the slogan "a diamond is forever".<ref name=sell>
{{cite web
|last=Epstein |first=E.J.
|title=Have You Ever Tried To Sell a Diamond?
|url=http://www.theatlantic.com/issues/82feb/8202diamond1.htm
|work=[[The Atlantic]]
|date=1982
|accessdate=2009-05-05
}}</ref>

Another example of successful diamond marketing is brown Australian diamonds. Brown-colored diamonds have always constituted a significant part of the diamond production. However they were considered worthless for jewelry; they were not even assessed on the [[diamond color]] scale, and were predominantly used for industrial purposes. However, the
attitude has changed drastically after the development of [[Argyle diamond mine]] in Australia in 1986. As a result of an aggressive marketing campaign, the brown diamonds have become acceptable gems.<ref>{{cite book|url=http://books.google.com/books?id=_WI86J88ydAC&pg=PA34|page=34|title=The nature of diamonds|author=George E. Harlow|publisher=Cambridge University Press|year=1998|isbn=0521629357}}</ref><ref>{{cite book|url=http://books.google.com/books?id=zNicdkuulE4C&pg=PA416|page=416|title=Industrial minerals & rocks|author=Jessica Elzea Kogel|publisher= Society for Mining, Metallurgy, and Exploration (U.S.)|year=2006|isbn=0873352335}}</ref>. The change was mostly due to the numbers: the Argyle mine, with its 35 million carats (7,000&nbsp;kg) of diamonds per year, makes about one-third of global production of natural diamonds;<ref>{{cite web|accessdate=2009-08-04|url=http://www.costellos.com.au/diamonds/industry.html|title=The Australian Diamond Industry}}</ref> 80% of Argyle diamonds are brown.<ref>{{cite book|url=http://books.google.com/books?id=068-M3xrDSQC&pg=PT158|page=158|title=}}</ref>

====Cutting====
{{main|Diamond cutting|Diamond cut}}
[[Image:Darya-e Noor Diamond of Iran.png|thumb|right|alt=A large rectangular pink multifaceted gemstone, set in a decorative surround. The decoration includes a row of small clear faceted gemstones around the main gem's perimeter, and clusters of gems forming a crest on one side. The crest comprises a three-pointed crown faced by two unidentifiable animals.|The [[Darya-ye Noor|Darya-I-Nur]] Diamond—an example of unusual diamond cut and jewelry arrangement]]
The mined rough diamonds are converted into gems through a multi-step process called "cutting".
Diamonds are extremely hard, but also brittle and can be split up by a single blow. Therefore, the diamond cutting is traditionally considered as a delicate procedure requiring skills, scientific knowledge, tools and experience. Its final goal is to produce a facetted jewel where the specific angles between the facets would optimize the diamond luster, that is dispersion of white light, whereas the number and area of facets would determine the weight of the final product. The weight reduction upon cutting is significant and can be of the order of 50%.<ref name=x50>{{cite book|url=http://books.google.com/books?id=jPT6JADCqgwC&pg=PA280|page=280|title=Handbook of carbon, graphite, diamond, and fullerenes: properties, processing, and applications|author=Pierson,Hugh O|publisher=William Andrew|year=1993|isbn=0815513399}}</ref> Several possible shapes are considered, but the final decision is often determined not only by scientific, but also practical considerations. For example the diamond might be intended for display or for wear, in a ring or a necklace, singled or surrounded by other gems of certain color and shape.<ref name=antique>{{cite book|url=http://books.google.com/books?id=Y84qRt6nz-8C&pg=PA88|pages=82-102|title=Antique jewellery: its manufacture, materials and design|author=James, Duncan S|publisher=Osprey Publishing|year=1998|isbn=0747803854}}</ref>

The most time-consuming part of the cutting is the preliminary analysis of the rough stone. It needs to address a large number of issues, bears much responsibility, and therefore can last years in case of unique diamonds. The following issues are being considered:
*The hardness of diamond and its ability to cleave strongly depend on the crystal orientation. Therefore, the crystallographic structure of the diamond to be cut is analyzed using [[X-ray diffraction]] in order to choose the optimal cutting directions.
*Most diamonds contain visible non-diamond inclusions and crystal flaws. The cutter has to decide which flaws are to be removed by the cutting and which could be kept.
*The diamond can be split by a single, well calculated blow of a hammer to a pointed tool, which is quick, but risky. Alternatively, it can be cut with a [[diamond saw]], which is a more reliable but tedious procedure.<ref name=antique/><ref>{{cite book|url=http://books.google.com/books?id=X3qe9jzYUAQC&pg=PA984|pages=984-992|title=Handbook of industrial diamonds and diamond films|author=Prelas, Mark Antonio; Popovici, Galina; Bigelow,Louis K.|publisher=CRC Press|year=1998|isbn=0824799941}}</ref>

After initial cutting, the diamond is shaped in numerous stages of polishing. Contrary to cutting, which is a responsible but quick operation, polishing removes material by gradual erosion and is extremely time consuming. However the associated technique is well developed; it is considered as a routine and can be performed by technicians.<ref>{{cite journal|url=http://books.google.com/books?id=i9kDAAAAMBAJ&pg=PA760|pages=760-764|title=Popular Mechanics|year=1940|volume=74|issue=5|issn=0032-4558|publisher=Hearst Magazines}}</ref> After polishing, the diamond is reexamined for possible flaws, either remaining or induced by the process. Those flaws are concealed through various [[diamond enhancement]] techniques, such as repolishing, crack filling, or clever arrangement of the stone in the jewelry. Remaining non-diamond inclusions are removed through laser drilling and filling of the produced voids.<ref name=read>{{cite book|url=http://books.google.com/books?id=t-OQO3Wk-JsC&pg=PA166|pages=165-166|title=Gemmology|author=Read, P. G.|publisher=Butterworth-Heinemann|year= 2005|isbn=0750664495}}</ref>

===Industrial uses===
[[Image:Dia scalpel.jpg|thumb|180 px|alt=A diamond scalpel consisting of a yellow diamond blade attached to a pen-shaped holder|A [[scalpel]] with synthetic diamond blade]]
[[File:Diamond blade very macro.jpg|thumb|alt=A polished metal slab embedded with small diamonds|Diamonds in an [[angle grinder]] blade]]

The market for industrial-grade diamonds operates much differently from its gem-grade counterpart. Industrial diamonds are valued mostly for their hardness and heat conductivity, making many of the gemological characteristics of diamonds, such as clarity and color, irrelevant for most applications. This helps explain why 80% of mined diamonds (equal to about 135&nbsp;million carats or 27&nbsp;[[Tonne|metric tons]] annually), unsuitable for use as gemstones, are destined for industrial use. In addition to mined diamonds, synthetic diamonds found industrial applications almost immediately after their invention in the 1950s; another 570&nbsp;million carats (114&nbsp;tons) of synthetic diamond is produced annually for industrial use. Approximately 90% of diamond grinding grit is currently of synthetic origin.<ref name=usgs>
{{cite web
|title=Industrial Diamonds Statistics and Information
|url=http://minerals.usgs.gov/minerals/pubs/commodity/diamond/
|work=[[United States Geological Survey]]
|accessdate=2009-05-05
}}</ref>

The boundary between gem-quality diamonds and industrial diamonds is poorly defined and partly depends on market conditions (for example, if demand for polished diamonds is high, some suitable stones will be polished into low-quality or small gemstones rather than being sold for industrial use). Within the category of industrial diamonds, there is a sub-category comprising the lowest-quality, mostly opaque stones, which are known as ''[[bort]]''.<ref name=spear>
{{cite book
|last=Spear|first=K.E |last2=Dismukes |first2=J.P.
|title=Synthetic Diamond: Emerging CVD Science and Technology
|url=http://books.google.com/books?id=RR5HF25DB7UC
|page=628
|publisher=[[John Wiley & Sons|Wiley]]–[[IEEE]]
|year=1994
|isbn=0471535893
}}</ref>

Industrial use of diamonds has historically been associated with their hardness; this property makes diamond the ideal material for cutting and grinding tools. As the hardest known naturally occurring material, diamond can be used to polish, cut, or wear away any material, including other diamonds. Common industrial adaptations of this ability include diamond-tipped [[drill bit]]s and saws, and the use of diamond powder as an [[abrasive]]. Less expensive industrial-grade diamonds, known as [[bort]], with more flaws and poorer color than gems, are used for such purposes.<ref>
{{cite book
|last=Holtzapffel |first=C.
|title=Turning And Mechanical Manipulation
|url=http://books.google.com/books?id=omwPAAAAYAAJ&pg=PA178
|publisher=Holtzapffel & Co
|pages=176–178
|year=1856
}}</ref> Diamond is however not suitable for machining [[ferrous]] [[alloy]]s at high speeds, as carbon is soluble in iron at the high temperatures created by high-speed machining, leading to greatly increased wear on diamond tools when compared to alternatives.<ref>
{{cite journal
|last=Coelho |first=R.T. |last2=Yamada |first2=S. |last3=Aspinwall |first3=D.K.
|last4=Wise |first4=M.L.H.
|title=The application of polycrystalline diamond (PCD) tool materials when drilling and reaming aluminum-based alloys including MMC
|journal=International Journal of Machine Tools and Manufacture
|volume=35 |issue=5 |pages=761–774
|year=1995
|doi=10.1016/0890-6955(95)93044-7
}}</ref>

Specialized applications include use in laboratories as containment for [[Pressure experiment|high pressure experiments]] (see [[diamond anvil cell]]), high-performance [[bearing (mechanical)|bearings]], and limited use in specialized [[window]]s.<ref name=spear/> With the continuing advances being made in the production of synthetic diamonds, future applications are becoming feasible. Garnering much excitement is the possible use of diamond as a [[semiconductor]] suitable to build [[integrated circuit|microchip]]s from, or the use of diamond as a [[heat sink]]<ref>
{{cite journal
|last=Sakamoto |first=M. |coauthors=''et al.''
|title=120&nbsp;W CW output power from monolithic AlGaAs (800&nbsp;nm) laser diode array mounted on diamond heatsink
|journal=[[Electronics Letters]]
|volume=28 |issue=2 |pages=197–199
|year=1992
|doi=10.1049/el:19920123
}}</ref> in electronics.

==Synthetics, simulants, and enhancements==
===Synthetics===
{{Main|Synthetic diamond}}
[[Image:HPHTdiamonds2.JPG|thumb|alt=Six crystals of cubo-octahedral shapes, each about 2 millimeters in diameter. Two are pale blue, one is pale yellow, one is gree-blue, one is dark blue and one green-yellow.|Synthetic diamonds of various colors grown by the high-pressure high-temperature technique]]
Synthetic diamonds are diamond crystals that are manufactured in a laboratory, as opposed to natural diamonds which form naturally within the Earth. The gemological and industrial uses of diamond have created a large demand for rough stones. This demand has been satisfied in large part by synthetic diamonds, which have been manufactured by various processes for more than half a century. However, in recent years it has become possible to produce gem-quality synthetic diamonds of significant size.<ref name="AMNH"/>

The majority of commercially available synthetic diamonds are yellow in color and produced by so called High Pressure High Temperature ([[HPHT]]) processes.<ref>{{cite journal
|last=Shigley |first=J.E. |coauthors=''et al.''
|title=Gemesis Laboratory Created Diamonds
|journal=Gems & Gemology
|volume=38 |issue=4 |pages=301–309
|year=2002
|doi=
}}</ref> The yellow color is caused by nitrogen impurities. Other colors may also be reproduced such as blue, green or pink, which are a result of the addition of boron or from irradiation after synthesis.<ref>
{{cite journal
|last=Shigley |first=J.E. |coauthors=''et al.''
|title=Lab Grown Colored Diamonds from Chatham Created Gems
|journal=Gems & Gemology
|volume=40 |issue=2 |pages=128–145
|year=2004
|doi=
}}</ref>

[[Image:Apollo synthetic diamond.jpg|thumb|right|alt=A round, clear gemstone with many facets, the main face being hexagonal, surrounded by many smaller facets.|Colorless gem cut from diamond grown by chemical vapor deposition]]
Another popular method of growing synthetic diamond is chemical vapor deposition (CVD). The growth occurs under low pressure (below atmospheric pressure). It involves feeding a mixture of gases (typically 1 to 99 [[methane]] to [[hydrogen]]) into a chamber and splitting them to chemically active [[Radical (chemistry)|radicals]] in a [[Plasma (physics)|plasma]] ignited by [[microwaves]], [[hot filament]], [[Electric arc|arc discharge]], [[welding torch]] or [[laser]].<ref name=CVD>
{{cite journal
|last=Werner |first=M. |coauthors=''et al.''
|title=Growth and application of undoped and doped diamond films
|journal=Reports on Progress in Physics
|volume=61 |page=1665
|year=1998
|doi=10.1088/0034-4885/61/12/002
}}</ref> This method is mostly used for coatings, but can also produce single crystals several millimeters in size (see picture).<ref name=yarnell/>

At present, the annual production of gem quality synthetic diamonds is only a few thousand carats, whereas the total production of natural diamonds is around 120&nbsp;million carats. Despite this fact, a purchaser is more likely to encounter a synthetic when looking for a fancy-colored diamond because nearly all synthetic diamonds are fancy-colored, while only 0.01% of natural diamonds are fancy-colored.<ref>{{cite book|url=http://books.google.com/books?id=zNicdkuulE4C&pg=PA428|pages=426–430|title=Industrial Minerals & Rocks|author=Kogel, J. E.|publisher=SME| year= 2006|isbn=0873352335}}</ref>

===Simulants===
{{Main|Diamond simulant}}
[[Image:MoissaniteRoundJewel.jpg|thumb|alt=A round sparkling, clear gemstone with many facets.|Gem-cut synthetic silicon carbide]]
A [[diamond simulant]] is defined as a non-diamond material that is used to simulate the appearance of a diamond. Diamond-simulant gems are often referred to as diamante. The most familiar diamond simulant to most consumers is [[cubic zirconia]]. The popular gemstone [[moissanite]] (silicon carbide) is often treated as a diamond simulant, although it is a gemstone in its own right. While moissanite does look similar to diamond, its main disadvantage as a diamond simulant is that cubic zirconia is far cheaper and arguably equally convincing. Both cubic zirconia and moissanite are produced synthetically.<ref>
{{cite book
|last=O'Donoghue |first=M. |last2=Joyner |first2=L.
|title=Identification of gemstones
|pages=12–19
|publisher=Butterworth-Heinemann |location=Great Britain
|year=2003
|isbn=0750655127
}}</ref>

===Enhancements===
{{Main|Diamond enhancement}}
Diamond enhancements are specific treatments performed on natural or synthetic diamonds (usually those already cut and polished into a gem), which are designed to better the gemological characteristics of the stone in one or more ways. These include laser drilling to remove inclusions, application of sealants to fill cracks, treatments to improve a white diamond's color grade, and treatments to give fancy color to a white diamond.<ref>{{cite book|url=http://books.google.com/books?id=kCc80Q4gzSgC&pg=PA115|page=115|title=The diamond formula|author=Barnard, A. S|publisher=Butterworth-Heinemann|year=2000|isbn=0750642440}}</ref>

Coatings are increasingly used to give a diamond simulant such as cubic zirconia a more "diamond-like" appearance. One such substance is [[diamond-like carbon]]—an amorphous carbonaceous material that has some physical properties similar to those of the diamond. Advertising suggests that such a coating would transfer some of these diamond-like properties to the coated stone, hence enhancing the diamond simulant. However, modern techniques such as [[Raman spectroscopy|Raman Spectroscopy]] should easily identify such a treatment.<ref>
{{cite journal
|last= Shigley |first=J.E.
|title=Observations on new coated gemstones
|journal=Gemmologie: Zeitschrift der Deutschen Gemmologischen Gesellschaft
|volume=56 |issue=1–2 |pages=53–56
|year=2007
}}</ref>

===Identification===
Early diamond identification tests included a scratch test relying on the superior hardness of diamond. This test is however destructive, as a diamond can scratch diamond, and is rarely used nowadays. Instead, diamond identification relies on its superior thermal conductivity. Electronic thermal probes are widely used in the gemological centers to separate diamonds from their imitations. These probes consist of a pair of battery-powered [[thermistor]]s mounted in a fine copper tip. One thermistor functions as a heating device while the other measures the temperature of the copper tip: if the stone being tested is a diamond, it will conduct the tip's thermal energy rapidly enough to produce a measurable temperature drop. This test takes about 2&ndash;3 seconds.<ref>J. F. Wenckus "Method and means of rapidly distinguishing a simulated diamond from natural diamond" {{US patent|4488821}} December 18, 1984</ref>

Whereas the thermal probe can separate diamonds from most of their simulants, distinguishing between various types of diamond, for example synthetic or natural, irradiated or non-irradiated, etc., requires more advanced, optical techniques. Those techniques are also used for some diamonds simulants, such as [[silicon carbide]], which pass the thermal conductivity test. Optical techniques can distinguish between natural diamonds and synthetic diamonds. They can also identify the vast majority of treated natural diamonds.<ref name=raman>{{cite book|url=http://books.google.com/books?id=W2cSkEsWbSkC&pg=PA387|pages=387–394|title=Raman spectroscopy in archaeology and art history|author=Edwards, H. G. M. and Chalmers, G. M|publisher=Royal Society of Chemistry|year=2005|isbn=0854045228}}</ref> "Perfect" crystals (at the atomic lattice level) have never been found, so both natural and synthetic diamonds always possess characteristic imperfections, arising from the circumstances of their crystal growth, that allow them to be distinguished from each other.<ref name=spot/>

Laboratories use techniques such as spectroscopy, microscopy and luminescence under shortwave ultraviolet light to determine a diamond's origin.<ref name=raman/> They also use specially made machines to aid them in the identification process. Two screening machines are the ''DiamondSure'' and the ''DiamondView'', both produced by the [[Diamond Trading Company|DTC]] and marketed by the [[Gemological Institute of America|GIA]].<ref>
{{cite web
|last=Donahue |first=P.J.
|title=DTC Appoints GIA Distributor of DiamondSure and DiamondView
|url=http://www.professionaljeweler.com/archives/news/2004/041904story.html
|work=Professional Jeweler Magazine
|date=2004-04-19
|accessdate=2009-03-02
}}</ref>

Several methods for identifying synthetic diamonds can be performed, depending on the method of production and the color of the diamond. [[Chemical vapor deposition|CVD]] diamonds can usually be identified by an orange fluorescence. D-J colored diamonds can be screened through the [[Swiss Gemmological Institute]]'s<ref>
{{cite web
|title=SSEF diamond spotter and SSEF illuminator
|url=http://dkamhi.com/ssef%20type%20IIa.htm
|publisher=SSEF Swiss Gemmological Institute
|accessdate=2009-05-05
}}</ref> Diamond Spotter. Stones in the D-Z color range can be examined through the DiamondSure UV/visible spectrometer, a tool developed by De Beers.<ref name=spot>
{{cite journal
|last=Welbourn |first=C.
|title=Identification of Synthetic Diamonds: Present Status and Future Developments<!--Proceedings of the 4th International Gemological Symposium-->
|journal=Gems & Gemology
|volume=42 |issue=3 |pages=34–35
|year=2006}}</ref> Similarly, natural diamonds usually have minor imperfections and flaws, such as inclusions of foreign material, that are not seen in synthetic diamonds.

==See also==
{{portalpar|Gemology and Jewelry|AEW diamond solo white.gif|35}}
*[[Diamond drilling]]
*[[List of famous diamonds]]
*[[List of minerals]]
*[[Diamonds as an investment]]

==References==
{{reflist|2}}

==Books==
*{{cite book|author=C. Even-Zohar|year=2007|title=From Mine to Mistress: Corporate Strategies and Government Policies in the International Diamond Industry|edition=2nd|publisher=Mining Journal Press|url=http://www.mine2mistress.com|isbn=}}
*{{cite book|author=G. Davies|year=1994|title=Properties and growth of diamond|publisher=INSPEC|isbn=0852968752}}
*{{cite book|author =M. O'Donoghue, M|title=Gems|publisher=Elsevier|year=2006|isbn=0750658568}}
*{{cite book|author=M. O'Donoghue and L. Joyner|year=2003|title=Identification of gemstones|publisher=Butterworth-Heinemann|location=Great Britain|isbn=0750655127}}
*{{cite book|author=A. Feldman and L.H. Robins|year=1991|title=Applications of Diamond Films and Related Materials|publisher=Elsevier|isbn=}}
*{{cite book|author=J.E. Field|year=1979|title=The Properties of Diamond|publisher=Academic Press|location=London|isbn=0122553500}}
*{{cite book|author=J.E. Field|year=1992|title=The Properties of Natural and Synthetic Diamond|publisher=Academic Press|location=London|isbn=0122553527}}
*{{cite book|author=W. Hershey|year=1940|title=The Book of Diamonds|publisher=Hearthside Press New York|url=http://books.google.com/books?id=35eij1e1al8C&printsec=frontcover|isbn =1417977159}}
*{{cite book|author=S. Koizumi, C.E. Nebel and M. Nesladek|year=2008|title=Physics and Applications of CVD Diamond|publisher=Wiley VCH|isbn=3527408010|url =http://books.google.com/books?id=pRFUZdHb688C}}
*{{cite book|author=L.S. Pan and D.R. Kani|year=1995|title=Diamond: Electronic Properties and Applications|publisher=Kluwer Academic Publishers|url=http://books.google.com/books?id=ZtfFEoXkU8wC&pg=PP1|isbn=0792395247}}
*{{cite book|author=Pagel-Theisen, Verena|year=2001|title=Diamond Grading ABC: the Manual|publisher=Rubin & Son|location=Antwerp|isbn=3980043460}}
*{{cite book|author=R.L. Radovic, P.M. Walker and P.A. Thrower|year=1965|title=Chemistry and physics of carbon: a series of advances|publisher=Marcel Dekker|location=New York|isbn=082470987X}}
*{{cite book|author=M. Tolkowsky|year=1919|title= Diamond Design: A Study of the Reflection and Refraction of Light in a Diamond|publisher=E. & F.N. Spon|location=London|url=http://www.folds.net/diamond/index.html|isbn=}}
*{{cite book|author=R.W. Wise|year=2003|title=Secrets Of The Gem Trade, The Connoisseur's Guide To Precious Gemstones|publisher=Brunswick House Pres|url=http://www.secretsofthegemtrade.com|isbn =}}
*{{cite book|author=A.M. Zaitsev|year=2001|title=Optical Properties of Diamond: A Data Handbook|publisher=Springer|url=http://books.google.com/books?id=msU4jkdCEhIC&pg=PP1|isbn =354066582X}}

==External links==
{{commons|Diamond}}
{{Wiktionary}}
* [http://www.ioffe.ru/SVA/NSM/Semicond/Diamond/index.html Properties of diamond: Ioffe database]
* [http://newton.ex.ac.uk/people/sque/diamond/structure/structure.html Interactive structure of bulk diamond] (Java applet)
* [http://www.pbs.org/wnet/nature/diamonds/index.html PBS Nature: Diamonds]
* [http://www.mnh.si.edu/exhibits/si-gems Smithsonian's Splendour of Diamonds exhibit]
* Epstein, Edward Jay (1982). [http://edwardjayepstein.com/diamond/prologue.htm ''The diamond invention''] (Complete book, includes "Chapter 20: [http://www.theatlantic.com/doc/198202/diamond Have you ever tried to sell a diamond?]" )
* [http://lgdl.gia.edu/pdfs/W97_fluoresce.pdf "A Contribution to the Understanding of Blue Fluorescence on the Appearance of Diamonds"]. (2007) [[Gemological Institute of America|Gemological_Institute_of_America (GIA)]]
* Tyson, Peter (November 2000). [http://www.pbs.org/wgbh/nova/diamond/sky.html "Diamonds in the Sky"]. Retrieved March 10, 2005.

*[[Human Rights Watch]] [[Child Labor]] News[http://www.hrw.org/en/category/topic/children%E2%80%99s-rights/labor] and Report [http://www.hrw.org/en/reports/2009/06/26/diamonds-rough-0]

<!--spacing, please do not remove-->

{{Allotropes of carbon}}
{{Jewellery}}

[[Category:Diamond| ]]
[[Category:Native element minerals]]
[[Category:Impact event minerals]]
[[Category:Economic geology]]
[[Category:Semiconductor materials]]
[[Category:Carbon]]
[[Category:Transparent materials]]
[[Category:Superhard materials]]
[[Category:Abrasives]]
[[Category:Greek loanwords]]

{{Link FA|hu}}
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{{Link FA|eo}}
<!--Interlanguage links-->

[[af:Diamant]]
[[ar:ألماس]]
[[an:Diamant]]
[[az:Almaz]]
[[zh-min-nan:Soān-chio̍h]]
[[be:Алмаз]]
[[be-x-old:Алмаз]]
[[bs:Dijamant]]
[[bg:Диамант]]
[[ca:Diamant]]
[[cs:Diamant]]
[[cy:Diemwnt]]
[[da:Diamant]]
[[de:Diamant]]
[[et:Teemant]]
[[el:Διαμάντι]]
[[es:Diamante]]
[[eo:Diamanto]]
[[eu:Diamante]]
[[fa:الماس]]
[[fo:Diamantar]]
[[fr:Diamant]]
[[gl:Diamante]]
[[hak:Tson-sa̍k]]
[[ko:다이아몬드]]
[[hy:Ադամանդ]]
[[hi:हीरा]]
[[hr:Dijamant]]
[[io:Diamanto]]
[[bpy:ডিয়ামান্টে]]
[[id:Intan]]
[[ia:Diamante]]
[[is:Demantur]]
[[it:Diamante]]
[[he:יהלום]]
[[kn:ವಜ್ರ]]
[[ka:ბრილიანტი]]
[[sw:Almasi]]
[[la:Adamas]]
[[lv:Dimants]]
[[lt:Deimantas]]
[[li:Diamaant]]
[[jbo:krilytabno]]
[[lmo:Diamant]]
[[hu:Gyémánt]]
[[mk:Дијамант]]
[[ml:വജ്രം (നവരത്നം)]]
[[mr:हिरा]]
[[ms:Berlian]]
[[mwl:Diamante]]
[[mn:Алмааз]]
[[nl:Diamant]]
[[ja:ダイヤモンド]]
[[no:Diamant]]
[[nn:Diamant]]
[[pl:Diament]]
[[pt:Diamante]]
[[ro:Diamant]]
[[qu:Q'ispi umiña]]
[[ru:Алмаз]]
[[sah:Алмаас]]
[[sq:Diamanti]]
[[simple:Diamond]]
[[sk:Diamant]]
[[sl:Diamant]]
[[sr:Дијамант]]
[[sh:Dijamant]]
[[fi:Timantti]]
[[sv:Diamant]]
[[tl:Diyamante]]
[[ta:வைரம்]]
[[te:వజ్రం]]
[[th:เพชร]]
[[tg:Алмос]]
[[tr:Elmas]]
[[uk:Алмаз]]
[[vi:Kim cương]]
[[war:Diamante]]
[[yi:בריליאנט]]
[[yo:Díámọ̀ndì]]
[[zh-yue:鑽石]]
[[zh:钻石]]

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'{{Otheruses4|the mineral|the gemstone|Diamond (gemstone)|other uses, including the shape <big>[[◊]]</big>}} {{featured article}} {{Infobox mineral |name = Diamond |category = Native Minerals |boxwidth = |boxbgcolor = #7da7d9 |image = Brillanten.jpg |alt = Seven clear faceted gems, six small stones of similar size and a large one. |caption = A scattering of round-brilliant cut diamonds shows off the many reflecting facets. |formula = [[Carbon|C]] |molweight = {{val|12.01|ul=g/mol}} |color = Typically yellow, brown or gray to colorless. Less often blue, green, black, translucent white, pink, violet, orange, purple and red. |habit = [[Octahedral]] |system = Isometric-Hexoctahedral ([[Cubic crystal system|Cubic]]) |twinning = |cleavage = 111 (perfect in four directions) |fracture = [[Conchoidal fracture|Conchoidal]] (shell-like) |mohs = 10 |luster = [[Lustre_(mineralogy)#Adamantine_lustre|Adamantine]] |polish = Adamantine |refractive = 2.418 (at 500 nm) |opticalprop = Singly Refractive |birefringence = None |dispersion = 0.044 |pleochroism = None |streak = colorless |gravity = {{val|3.52|0.01}} |density = 3.5–{{val|3.53|ul=g/cm3}} hardness =10(hardest mineral or gem) |[[Transparency (optics)|diaphaneity]] = [[Transparency (optics)|Transparent]] to subtransparent to translucent |references = <ref name=mindat>{{cite web|publisher=Mindat|title=Diamond|url=http://www.mindat.org/min-1282.html|accessdate=2009-07-07}}</ref><ref name=webmin>{{cite web|publisher=WebMineral|title=Diamond|url=http://webmineral.com/data/Diamond.shtml|accessdate=2009-07-07}}</ref>}} In [[mineralogy]], '''diamond''' (from the ancient [[Greek language|Greek]] adámas, meaning "proper" or "unalterable") is an [[Allotropes of carbon|allotrope of carbon]], where the [[carbon]] atoms are arranged in a variation of the [[face-centered cubic]] crystal structure called a [[diamond lattice]]. Diamond is the second most stable form of carbon, after [[graphite]]; however, the conversion rate from diamond to graphite is negligible at [[Standard conditions for temperature and pressure|ambient conditions]]. Diamond is specifically renowned as a material with superlative physical qualities, most of which originate from the strong [[covalent bond]]ing between its atoms. In particular, diamond has the highest [[Hardness#Scratch hardness|hardness]] and [[thermal conductivity]] of any bulk material synthesized so far. Those properties determine the major industrial application of diamond in cutting and polishing tools. Diamond has remarkable optical characteristics. Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as [[boron]] and [[nitrogen]]. Combined with the wide transparency, this results in clear, colorless appearance of most natural diamonds. Small amounts of defects or impurities (about one per million of lattice atoms) color diamond blue (boron), yellow (nitrogen), brown ([[Dislocation|lattice defects]]), green, purple, pink, orange or red. Diamond also has relatively high [[optical dispersion]], that is ability to disperse light of different colors, which results in its characteristic [[luster (mineralogy)|luster]]. Excellent optical and mechanical properties, combined with efficient marketing, make diamond the most popular [[gemstone]]. Most natural diamonds are formed at high-pressure high-temperature conditions existing at depths of {{convert|140|to|190|sp=us|km}} in the Earth [[Mantle (geology)|mantle]]. Carbon-containing minerals provide the carbon source, and the growth occurs over periods from 1&nbsp;billion to 3.3&nbsp;billion years, which respectively corresponds to roughly 25% and 75% of the [[age of the Earth]]. Diamonds are brought close to the Earth surface through deep volcanic eruptions by a [[magma]], which cools into [[igneous rock]]s known as [[kimberlite]]s and [[lamproite]]s. Diamonds can also be produced synthetically in a [[Synthetic diamond#High pressure, high temperature|high-pressure high-temperature]] process which approximately simulates the conditions in the Earth mantle. An alternative, and completely different growth technique is [[chemical vapor deposition]]. Several non-diamond materials, which include [[cubic zirconia]] and [[silicon carbide]] and are often called [[diamond simulants]], resemble diamond in appearance and many properties. Special [[Gemology|gemological]] techniques have been specially developed to distinguish natural and [[synthetic diamond]]s and diamond simulants. ==History== {{See also|Diamond (gemstone)}} The name ''diamond'' is derived from the [[Greek language|ancient Greek]] ''ἀδάμας'' ''(adámas''), "proper", "unalterable", "unbreakable, untamed", from [[:wiktionary:ἀ-|ἀ-]] (a-), "un-" + ''δαμάω'' (''damáō''), "I overpower, I tame".<ref> {{cite web |last=Liddell |first=H.G. |last2=Scott |first2=R. |title=Adamas |work=A Greek-English Lexicon |url=http://www.perseus.tufts.edu/cgi-bin/ptext?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3D%231145 |publisher=[[Perseus Project]] }}</ref> However, diamonds are thought to have been first recognized and mined in India, where significant [[alluvial deposit]]s of the stone could then be found many centuries ago along the rivers [[Penner River|Penner]], [[Krishna River|Krishna]] and [[Godavari River|Godavari]]. Diamonds have been known in India for at least 3,000 years but most likely 6,000 years.<ref name=hershey> {{cite book |url=http://books.google.com/books?id=35eij1e1al8C&pg=PA23 |last=Hershey |first=W. |title=The Book of Diamonds |publisher=Hearthside Press |location=New York |year=1940 |pages=22–28 |isbn=1417977159 }}</ref> Diamonds have been treasured as gemstones since their use as [[icon|religious icons]] in [[Kingdoms of Ancient India|ancient India]]. Their usage in engraving tools also dates to early [[History of the world|human history]].<ref> {{cite book |author=[[Pliny the Elder]] |title=Natural History: A Selection |publisher=[[Penguin Books]] |page=371 |year=2004 |isbn=0140444130 }}</ref><ref name=ancient_China> {{cite news |title=Chinese made first use of diamond |url=http://news.bbc.co.uk/2/hi/science/nature/4555235.stm |publisher=[[BBC News]] |date=2005-05-17 |accessdate=2007-03-21 }}</ref> Popularity of diamonds has risen since the 19th century because of increased supply, improved cutting and polishing techniques, growth in the world economy, and innovative and successful advertising campaigns.<ref name=sell/> In 1813, [[Humphry Davy]] used a lens to concentrate the rays of the sun on a diamond in an atmosphere of [[oxygen]], and showed that the only product of the combustion was [[carbon dioxide]], proving that diamond is composed of carbon. Later, he showed that in an atmosphere devoid of oxygen, diamond is converted to graphite.<ref> {{cite book |last=Thomas |first=J.M.L. |title=Michael Faraday and the Royal Institution: The Genius of Man and Place |publisher=Adam Hilger |location=Bristol |year=1991 |page=19 |isbn=0-7503-0145-7 }}</ref> The most familiar usage of diamonds today is as gemstones used for [[adornment]], a usage which dates back into antiquity. The [[Dispersion (optics)|dispersion]] of white light into [[spectral color]]s is the primary gemological characteristic of gem diamonds. In the twentieth century, experts in the field of [[gemology]] have developed methods of grading diamonds and other gemstones based on the characteristics most important to their value as a gem. Four characteristics, known informally as the ''four Cs'', are now commonly used as the basic descriptors of diamonds: these are ''carat'', ''cut'', ''color'', and ''clarity''.<ref>{{cite book|url=http://books.google.com/books?id=DIWEi5Hg93gC&pg=PA42|page=42|author=Hesse, R. W.|title=Jewelrymaking through history| publisher=Greenwood Publishing Group| year= 2007|isbn=0313335079}}</ref> ==Material properties== {{Main|Material properties of diamond|Crystallographic defects in diamond}} [[Image:Diamond and graphite2.jpg|thumb|alt=Four panels. First, seven clear faceted gems, six small and a large one. Second, black material with uneven surface. Third, three parallel atomic sheets, each resembling a chicken wire hedge. Fourth, a boxed atomic structure containing tetrahedrally arranged balls connected by 0.15 nm bonds.|Diamond and graphite are two [[allotrope]]s of [[carbon]]: pure forms of the same element that differ in structure.]] A diamond is a [[transparency (optics)|transparent]] [[crystal]] of [[Tetrahedral-octahedral honeycomb|tetrahedrally]] bonded carbon atoms ([[Orbital hybridisation|sp<sup>3</sup>]]) that crystallizes into the [[Diamond cubic|diamond lattice]] which is a variation of the [[face centered cubic]] structure. Diamonds have been adapted for many uses because of the material's exceptional physical characteristics. Most notable are its extreme hardness and [[thermal conductivity]] (900–{{val|2320|u=W·m{{sup|−1}}·K{{sup|−1}}}}),<ref name=PNU> {{cite journal |last=Wei |first=L. |coauthors=''et al.'' |title=Thermal conductivity of isotopically modified single crystal diamond |journal=Physical Review Letters |volume=70 |page=3764 |year=1993 |doi =10.1103/PhysRevLett.70.3764 }}</ref> as well as wide [[bandgap]] and high optical [[dispersion (optics)|dispersion]].<ref name=walker/> Above {{val|1700|ul=degC}} ({{val|1973|ul=K}} / {{val|3583|ul=degF}}) in [[vacuum]] or oxygen-free atmosphere, diamond converts to graphite; in air, transformation starts at ~{{val|700|u=degC}}.<ref>{{cite journal| doi =10.1016/S0925-9635(01)00673-2| title =The oxidation of (100) textured diamond| year =2002| author =John, P| journal =Diamond and Related Materials| volume =11| page=861}}</ref> Naturally occurring diamonds have a density ranging from 3.15–{{val|3.53|u=g/cm3}}, with pure diamond close to {{val|3.52|u=g/cm3}}.<ref name=mindat/> Despite the hardness of diamonds, the chemical bonds that hold the carbon atoms in diamonds together are actually weaker than those that hold together the other form of pure carbon, graphite. The difference is that in diamonds, the bonds form an inflexible three-dimensional lattice. In graphite, the atoms are tightly bonded into sheets, which can slide easily however.<ref name=Pop>{{cite journal |last=Gray |first=Theodore |title=Gone in a Flash |journal=Popular Science |page=70 |month=September |year=2009 }}</ref> ===Hardness=== Diamond is the hardest natural material known, where hardness is defined as resistance to scratching and is graded between 1 (softest) and 10 (hardest) using the [[Mohs scale of mineral hardness]]. Diamond has a hardness of 10 (hardest) on this scale.<ref name=read>{{cite book|url=http://books.google.com/books?id=t-OQO3Wk-JsC&pg=PA49|pages=49–50|title=Gemmology|author=Read, P. G.|publisher=Butterworth-Heinemann|year= 2005|isbn=0750664495}}</ref> Diamond's hardness has been known since antiquity, and is the source of its name. The diamond hardness depends on its purity, crystalline perfection and orientation: hardness is higher for flawless, pure crystals oriented to the [[Miller_index#Case_of_the_cubic_structures|<111>]] direction (along the longest diagonal of the cubic diamond lattice).<ref>{{cite book|pages=142–147|url=http://books.google.com/books?id=jtC1mUFZfQcC&pg=PA143|title=Properties, Growth and Applications of Diamond|author=Neves, A. J. and Nazaré, M. H.|publisher=[[Institution of Engineering and Technology]]|year= 2001|isbn=0852967853}}</ref> Therefore, whereas it might be possible to scratch some diamonds with other materials, such as [[boron nitride]], the hardest diamonds can only be scratched by other diamonds. In particular, [[Aggregated diamond nanorod|nanocrystalline diamond aggregates]] were measured to be harder than any large single crystal diamond. Those aggregates are produced by high-pressure high-temperature treatment of [[graphite]] or [[fullerite]] (C<sub>60</sub>).<ref name=blank> {{cite journal |last=Blank |first=V. |coauthors=''et al.'' |title=Ultrahard and superhard phases of fullerite C<sub>60</sub>: comparison with diamond on hardness and wear |url=http://www.nanoscan.info/files/article_03.pdf |journal=Diamond and Related Materials |volume=7 |issue=2–5|page=427–431 |year=1998 |doi=10.1016/S0925-9635(97)00232-X }}</ref> The hardness of diamonds contributes to its suitability as a gemstone. Because it can only be scratched by other diamonds, it maintains its polish extremely well. Unlike many other gems, it is well-suited to daily wear because of its resistance to scratching—perhaps contributing to its popularity as the preferred gem in [[engagement ring|engagement]] or [[wedding ring]]s, which are often worn every day. The hardest natural diamonds mostly originate from the Copeton and Bingara fields located in the [[New England (Australia)|New England]] area in [[New South Wales]], Australia. These diamonds are generally small, perfect to semiperfect octahedra, and are used to polish other diamonds. Their hardness is associated with the [[crystal growth]] form, which is single-stage crystal growth. Most other diamonds show more evidence of multiple growth stages, which produce inclusions, flaws, and defect planes in the crystal lattice, all of which affect their hardness. It is possible to treat regular diamonds under a combination of high pressure and high temperature to produce diamonds that are harder than the diamonds used in hardness gauges.<ref name="Smithsonian"> {{cite journal |last=Boser |first=U. |title=Diamonds on Demand |url=http://www.smithsonianmag.com/science-nature/diamonds-on-demand.html |journal=[[Smithsonian (magazine)|Smithsonian]] |volume=39 |issue=3 |pages=52–59 |year=2008 |doi= }}</ref> Somewhat related to hardness is another mechanical property ''toughness'', which is a material's ability to resist breakage from forceful impact. The [[toughness]] of natural diamond has been measured as {{val|2.0|u=[[Megapascal|MPa]]·[[meter|m]]<sup>1/2</sup>}},<ref> {{cite book |last=Weber |first=M.J. |title=Handbook of optical materials |url=http://books.google.de/books?id=6VpQDoef05wC |page=119 |publisher=[[CRC Press]] |year=2002 |isbn=0849335124 }}</ref> and the critical stress intensity factor is {{val|3.4|u=[[Meganewton|MN]]·[[meter|m]]<sup>−3/2</sup>}}.<ref> {{cite journal |last=Field |first=J.E. |title=Strength and Fracture Properties of Diamond |journal=[[Philosophical Magazine A]] |volume=43 |issue=3 |pages=595–618 |publisher=[[Taylor & Francis]] |year=1981 |doi=10.1080/01418618108240397 }}</ref> Those values are good compared to other gemstones, but poor compared to most engineering materials. As with any material, the macroscopic geometry of a diamond contributes to its resistance to breakage. Diamond has a cleavage plane and is therefore more fragile in some orientations than others. [[Diamond cutting|Diamond cutters]] use this attribute to cleave some stones, prior to faceting.<ref name=harlow/> ===Electrical conductivity=== Other specialized applications also exist or are being developed, including use as [[semiconductor]]s: some blue diamonds are natural semiconductors, in contrast to most other diamonds, which are excellent electrical [[Electrical insulation|insulator]]s.<ref name="boron"/> The conductivity and blue color originate from the boron impurity. Boron substitutes for carbon atoms in the diamond lattice, donating a hole into the valence band.<ref name="boron"> {{cite journal |last=Collins |first=A.T. |title=The Optical and Electronic Properties of Semiconducting Diamond |journal=[[Philosophical Transactions of the Royal Society A]] |volume=342 |pages=233–244 |year=1993 |doi=10.1098/rsta.1993.0017 }}</ref> Substantial conductivity is commonly observed in nominally undoped diamond grown by [[Chemical vapor deposition of diamond|chemical vapor deposition]]. This conductivity is associated with hydrogen-related species adsorbed at the surface, and it can be removed by annealing or other surface treatments.<ref name="Landstrass"> {{cite journal |last=Landstrass |first=M.I. |last2=Ravi |first2=K.V. |title=Resistivity of chemical vapor deposited diamond films |journal=[[Applied Physics Letters]] |volume=55 |pages=975–977 |year=1989 |doi=10.1063/1.101694 }}</ref><ref> {{cite journal |last=Zhang |first=W. |last2=Ristein |first2=J. |last3=Ley |first3=L. |title=Hydrogen-terminated diamond electrodes. II. Redox activity |journal=[[Physical Review E]] |volume=78 |page=041603 |year=2008 |doi=10.1103/PhysRevE.78.041603 }}</ref> ===Color=== {{Main|Diamond color}} [[Image:National Museum of Natural History Gold Colored Diamonds.JPG|alt=A museum display of jewelry items. Three brooches each consist of a large brown central gem surrounded by many clear small stones. A necklace has a large brown gem at its bottom and its string is all covered with small clear gems. A cluster-shaped decoration contains many brown gems.|300px|thumb|Brown colored diamonds at the [[National Museum of Natural History]] in [[Washington, D.C]]]] Diamond has a wide bandgap of {{val|5.5|ul=eV}} corresponding to the deep [[ultraviolet]] wavelength of 225 nanometers. This means pure diamond should transmit visible light and appear as a clear colorless crystal. Colors in diamond originate from lattice defects and impurities. The diamond crystal lattice is exceptionally strong and only atoms of nitrogen, boron and hydrogen can be introduced into diamond during the growth at significant concentrations (up to atomic percents). Transition metals Ni and Co, which are commonly used for growth of synthetic diamond by the high-pressure high-temperature techniques, have been detected in diamond as individual atoms, however the maximum concentration is 0.01% for Ni<ref> {{cite journal |last=Collins |first=A.T. |coauthors=''et al.'' |title=Correlation between optical absorption and EPR in high-pressure diamond grown from a nickel solvent catalyst |journal=Diamond and Related Materials |volume=7 |pages=333–338 |year=1998 |doi=10.1016/S0925-9635(97)00270-7 }}</ref> and even much less for Co. Note however, that virtually any element can be introduced in diamond by ion implantation.<ref name=zaitsev> {{cite journal|doi=10.1103/PhysRevB.61.12909|title=Vibronic spectra of impurity-related optical centers in diamond|year=2000|author=Zaitsev, A. M.|journal=Physical Review B|volume=61|pages=12909}}</ref> Nitrogen is by far the most common impurity found in gem diamonds. Nitrogen is responsible for the yellow and brown in diamonds. Boron is responsible for the gray blue colors.<ref name=walker> {{cite journal |last=Walker |first=J. |title=Optical absorption and luminescence in diamond |journal=Reports on Progress in Physics |volume=42 |page=1605–1659 |year=1979 |doi=10.1088/0034-4885/42/10/001 }}</ref> Color in diamond has two additional sources: irradiation (usually by alpha particles), that causes the color in green diamonds; and physical deformation of the diamond crystal known as plastic deformation. Plastic deformation is the cause of color in some brown<ref> {{cite journal |last=Hounsome |first=L.S. |coauthors=''et al.'' |title=Origin of brown coloration in diamond |journal=[[Physical Review B]] |volume=73 |pages=125203 |year=2006 |doi=10.1103/PhysRevB.73.125203 }}</ref> and perhaps pink and red diamonds.<ref> {{cite book |last=Wise |first=R.W. |title=Secrets Of The Gem Trade, The Connoisseur's Guide To Precious Gemstones |publisher=Brunswick House Press |pages=223–224 |year=2001 |isbn=9780972822381 }}</ref> In order of rarity, colorless diamond, by far the most common, is followed by yellow and brown, by far the most common colors, then by blue, green, black, translucent white, pink, violet, orange, purple, and the rarest, red.<ref name=harlow/> "Black", or [[Carbonado]], diamonds are not truly black, but rather contain numerous dark inclusions that give the gems their dark appearance. Colored diamonds contain impurities or structural defects that cause the coloration, while pure or nearly pure diamonds are transparent and colorless. Most diamond impurities replace a carbon atom in the [[crystal lattice]], known as a [[carbon flaw]]. The most common impurity, nitrogen, causes a slight to intense yellow coloration depending upon the type and concentration of nitrogen present.<ref name=harlow/> The [[Gemological Institute of America]] (GIA) classifies low saturation yellow and brown diamonds as diamonds in the ''normal color range'', and applies a grading scale from "D" (colorless) to "Z" (light yellow). Diamonds of a different color, such as blue, are called ''fancy colored'' diamonds, and fall under a different grading scale.<ref name=harlow/> In 2008, the [[Wittelsbach Diamond]], a {{convert|35.56|carat|g}} blue diamond once belonging to the King of Spain, fetched over US$24 million at a Christie's auction.<ref> {{cite news |last=Khan |first=U |title=Blue-grey diamond belonging to King of Spain has sold for record 16.3 GBP |url=http://www.telegraph.co.uk/culture/3703861/Blue-grey-diamond-belonging-to-King-of-Spain-has-sold-for-record-16.3m.html |publisher=[[The Daily Telegraph|The Telegraph]] }}</ref> In 2009 a {{convert|7.03|carat|g}} blue diamond fetched the highest price per-carat ever paid for a diamond when it was sold at auction for 10.5 million Swiss francs (6.97 million Euro or US$9.5 million at the time) which is in excess of US$1.3 million per carat.<ref> {{cite news |last=Nebehay |first=S. |title=Rare blue diamond sells for record $9.5 million |url=http://www.reuters.com/article/artsNews/idUSTRE54B6O020090512 |publisher=[[Reuters]] |date=2009-05-12 |accessdate=2009-05-13 }}</ref> ===Identification=== Diamonds can be identified by their high thermal conductivity. Their high [[refractive index]] is also indicative, but other materials have similar refractivity. Diamonds do cut glass, but this does not positively identify a diamond because other materials, such as quartz, also lie above glass on the [[Mohs scale]] and can also cut glass. Diamonds can scratch other diamonds, but this can result in damage to one or both stones. Hardness tests are infrequently used in practical gemology because of their potentially destructive nature.<ref name=read/> The extreme hardness and high value of diamond means that gems are typically polished slowly using painstaking traditional techniques and greater attention to detail than is the case with most other gemstones;<ref>{{cite book|url=http://books.google.com/books?id=fNJQok6N9_MC&pg=PA7|page=7|title=The diamond makers|author=Hazen, R. M|publisher=Cambridge University Press|year=1999|isbn=0521654742}}</ref> these tend to result in extremely flat, highly polished facets with exceptionally sharp facet edges. Diamonds also possess an extremely high refractive index and fairly high dispersion. Taken together, these factors affect the overall appearance of a polished diamond and most diamantaires still rely upon skilled use of a [[loupe]] (magnifying glass) to identify diamonds 'by eye'.<ref>{{cite book|url=http://books.google.com/books?id=Jm3FwBiHaI4C&pg=PA37|pages=34–37|title=Synthetic, Imitation and Treated Gemstones|author=O'Donoghue, M.|publisher=Gulf Professional Publishing|year= 1997|isbn=0750631732}}</ref> ==Natural history== The formation of natural diamond requires very specific conditions—exposure of carbon-bearing materials to high pressure, ranging approximately between 45 and 60 [[Bar (unit)|kilobar]]s, but at a comparatively low temperature range between approximately 1650–2370 °F (900–1300 °C). These conditions are met in two places on Earth; in the [[Lithosphere|lithospheric mantle]] below relatively stable [[continental plate]]s, and at the site of a meteorite strike.<ref name=core>{{cite book|title=The Mantle and Core|author= Carlson, R.W.|url=http://books.google.com/books?id=1clZ4ABsfoAC&pg=PA248|page=248|publisher =Elsevier|year= 2005|isbn=0080448488}}</ref> ===Formation in cratons=== The conditions for diamond formation to happen in the lithospheric mantle occur at considerable depth corresponding to the aforementioned requirements of temperature and pressure. These depths are estimated between 140 and 190&nbsp;km though occasionally diamonds have crystallized at depths about 300&nbsp;km as well.<ref name="AMNH"/> The rate at which [[geothermal gradient|temperature changes with increasing depth]] into the Earth varies greatly in different parts of the Earth. In particular, under oceanic plates the temperature rises more quickly with depth, beyond the range required for diamond formation at the depth required. The correct combination of temperature and pressure is only found in the thick, ancient, and stable parts of [[continental plate]]s where regions of lithosphere known as ''[[craton]]s'' exist. Long residence in the cratonic lithosphere allows diamond crystals to grow larger.<ref name="AMNH"> {{cite book |last=Erlich |first=E.I. |last2=Dan Hausel |first2=W. |title=Diamond Deposits |url=http://books.google.com/books?id=068-M3xrDSQC&printsec=frontcover |pages=74–94 |publisher=Society for Mining, Metallurgy, and Exploration |year=2002 |isbn=0873352130 }}</ref> [[Image:Rough diamond.jpg|left|thumb|250px|alt=A clear octahedral stone protrudes from a black rock.|The slightly misshapen [[octahedral]] shape of this rough diamond crystal in matrix is typical of the mineral. Its lustrous faces also indicate that this crystal is from a primary deposit.]] Through studies of carbon [[isotope]] ratios (similar to the methodology used in [[carbon dating]], except with the [[stable isotope]]s [[Carbon-12|C-12]] and [[Carbon-13|C-13]]), it has been shown that the carbon found in diamonds comes from both inorganic and organic sources. Some diamonds, known as [[Peridotite|''harzburgitic'']], are formed from inorganic carbon originally found deep in the Earth's [[Mantle (geology)|mantle]]. In contrast, [[eclogite|''eclogitic'']] diamonds contain organic carbon from organic [[detritus]] that has been pushed down from the surface of the Earth's [[crust (geology)|crust]] through [[subduction]] (see [[plate tectonics]]) before transforming into diamond. These two different source of carbons have measurably different <sup>13</sup>C:<sup>12</sup>C ratios. Diamonds that have come to the Earth's surface are generally quite old, ranging from under 1&nbsp;[[1000000000 (number)|billion]] to 3.3&nbsp;billion years old. This is 22% to 73% of the [[age of the Earth]].<ref name="AMNH"/> Diamonds occur most often as [[euhedral]] or rounded [[octahedron|octahedra]] and [[Crystal twinning|twinned]] octahedra known as ''macles''. As diamond's crystal structure has a cubic arrangement of the atoms, they have many [[facet]]s that belong to a [[Cube (geometry)|cube]], [[octahedron]], [[rhombicosidodecahedron]], [[tetrakis hexahedron]] or [[disdyakis dodecahedron]]. The crystals can have rounded off and unexpressive edges and can be elongated. Sometimes they are found grown together or form double "twinned" crystals at the surfaces of the octahedron. These different shapes and habits of the diamonds result from differing external circumstances. Diamonds (especially those with rounded crystal faces) are commonly found coated in ''nyf'', an opaque gum-like skin.<ref> {{cite book |last=Webster |first=R. |last2=Read |first2=P.G. |title=Gems: Their sources, descriptions and identification |edition=5th |page=17 |publisher=[[Butterworth-Heinemann]] |location=Great Britain |year=2000 |isbn=0-7506-1674-1 }}</ref> ===Formation in meteorite impact craters=== Diamonds can also form in other natural high-pressure events. Very small diamonds of micrometer and nanometer sizes, known as ''microdiamonds'' or ''nanodiamonds'' respectively, have been found in meteorite [[impact crater]]s. Such impact events create shock zones of high pressure and temperature suitable for diamond formation. Impact-type microdiamonds can be used as an indicator of ancient impact craters.<ref name=core/> ===Extraterrestrial formation=== Not all diamonds found on Earth originated here. A type of diamond called [[carbonado]] diamond that is found in South America and Africa may have been deposited there via an asteroid impact (not formed from the impact) about 3&nbsp;billion years ago. These diamonds may have formed in the intrastellar environment, but as of 2008, there was no scientific consensus on how [[carbonado]] diamonds originated.<ref name=Garai2006> {{cite journal |first=J. |last=Garai |last2=Haggerty |first2=S.E. |last3=Rekhi |first3=S. |last4=Chance |first4=M. |year=2006 |title=Infrared Absorption Investigations Confirm the Extraterrestrial Origin of Carbonado Diamonds |journal=[[Astrophysical Journal]] |volume=653 |issue=2 |pages=L153–L156 |doi=10.1086/510451 }}</ref><ref name=Carbonardo> {{cite web |title=Diamonds from Outer Space: Geologists Discover Origin of Earth's Mysterious Black Diamonds |url=http://www.nsf.gov/news/news_summ.jsp?cntn_id=108270&org=NSF |publisher=[[National Science Foundation]] |date=2007-01-08 |accessdate=2007-10-28 }}</ref> [[Presolar grains]] in many meteorites found on Earth contain nanodiamonds of extraterrestrial origin, probably formed in [[supernova]]s. Scientific evidence indicates that [[white dwarf]] stars have a core of crystallized carbon and oxygen nuclei. The largest of these found in the universe so far, [[BPM 37093]], is located {{convert|50|ly|km}} away in the constellation [[Centaurus]]. A news release from the [[Harvard-Smithsonian Center for Astrophysics]] described the {{convert|2500|mi|adj=on}} wide stellar core as a ''diamond''.<ref> {{cite news |title=This Valentine's Day, Give The Woman Who Has Everything The Galaxy's Largest Diamond |url=http://cfa-www.harvard.edu/press/archive/pr0407.html |publisher=Center for Astrophysics |date= |accessdate=2009-05-05 }}</ref> It was referred to as ''Lucy'', after the Beatles song "Lucy in the Sky With Diamonds".<ref name="Smithsonian" /><ref> {{cite web |last=Cauchi |first=S. |title=Biggest Diamond Out of This World |url=http://www.theage.com.au/articles/2004/02/17/1076779973101.html |work=[[The Age]] |date=2004-02-18 |accessdate=2007-11-11 }}</ref> ===Surfacing=== [[Image:VolcanicPipe.jpg|right|thumb|float|220px|alt=Schematic cross section of an underground region 3 km deep and 2 km wide. A red dike stretches across the bottom, and a pipe containing some xenoliths runs from the dike to the surface, varing from red at the bottom to orange-yellow at the top. The pipe's root, at its bottom, is about 1 km long, and its diatreme, above the root, is about 1.5 km long. The pipe's top is a crater, rimmed by a tuff ring and containing washed-back ejecta. The erosion level is almost zero for Orapa, about 1 km for Jagersfontein, and about 1.4 km for Kimberley.|Schematic diagram of a [[volcanic pipe]]]] Diamond-bearing rock is brought close to the surface through deep-origin volcanic eruptions. The [[magma]] for such a volcano must originate at a depth where diamonds can be formed<ref name="AMNH"/>—{{convert|150|km|mi|abbr=on|lk=off}} or more (three times or more the depth of source magma for most volcanoes). This is a relatively rare occurrence. These typically small surface volcanic craters extend downward in formations known as [[volcanic pipe]]s.<ref name="AMNH"/> The pipes contain material that was transported toward the surface by volcanic action, but was not ejected before the volcanic activity ceased. During eruption these pipes are open to the surface, resulting in open circulation; many [[xenolith]]s of surface rock and even wood and/or fossils are found in volcanic pipes. Diamond-bearing volcanic pipes are closely related to the oldest, coolest regions of [[continental crust]] ([[craton]]s). This is because cratons are very thick, and their [[lithosphere|lithospheric]] mantle extends to great enough depth that diamonds are stable. Not all pipes contain diamonds, and even fewer contain enough diamonds to make mining economically viable.<ref name="AMNH"/> The magma in volcanic pipes is usually one of two characteristic types, which cool into [[igneous rock]] known as either [[kimberlite]] or [[lamproite]].<ref name="AMNH"/> The magma itself does not contain diamond; instead, it acts as an elevator that carries deep-formed rocks (xenoliths), minerals ([[xenocryst]]s), and fluids upward. These rocks are characteristically rich in [[magnesium]]-bearing [[olivine]], [[pyroxene]], and [[amphibole]] minerals<ref name="AMNH"/> which are often altered to [[serpentine]] by heat and fluids during and after eruption. Certain ''indicator minerals'' typically occur within diamantiferous kimberlites and are used as mineralogical tracers by prospectors, who follow the indicator trail back to the volcanic pipe which may contain diamonds. These minerals are rich in [[chromium]] (Cr) or [[titanium]] (Ti), elements which impart bright colors to the minerals. The most common indicator minerals are chromium [[garnet]]s (usually bright red chromium-[[pyrope]], and occasionally green ugrandite-series garnets), eclogitic garnets, orange titanium-pyrope, red high-chromium [[spinel]]s, dark [[chromite]], bright green chromium-[[diopside]], glassy green [[olivine]], black [[ilmenite|picroilmenite]], and [[magnetite]]. Kimberlite deposits are known as ''blue ground'' for the deeper serpentinized part of the deposits, or as ''yellow ground'' for the near surface [[smectite]] [[clay]] and carbonate [[weathering|weathered]] and [[oxidation|oxidized]] portion.<ref name="AMNH"/> Once diamonds have been transported to the surface by magma in a volcanic pipe, they may erode out and be distributed over a large area. A volcanic pipe containing diamonds is known as a ''primary source'' of diamonds. ''Secondary sources'' of diamonds include all areas where a significant number of diamonds, eroded out of their kimberlite or lamproite matrix, and accumulated because of water or wind action. These include [[alluvium|alluvial]] deposits and deposits along existing and ancient shorelines, where loose diamonds tend to accumulate because of their approximate size and density. Diamonds have also rarely been found in deposits left behind by glaciers (notably in [[Wisconsin]] and [[Indiana]]); however, in contrast to alluvial deposits, glacial deposits are minor and are therefore not viable commercial sources of diamond.<ref name="AMNH"/> ==Production== [[Image:Diamond output2.PNG|thumb|right|350px|alt=A world map showing that roughly half of diamonds originate from Africa, and one-third from Australia. The remaining part is mostly due to Russia with minor contribution from Canada and China.|Diamond output in 2005]] {{See also|List of diamond mines}} Approximately 130&nbsp;million [[Carat (mass)|carats]] ({{convert|26000|kg|abbr=on}}) of diamonds are mined annually, with a total value of nearly US$9&nbsp;[[1000000000 (number)|billion]], and about {{convert|100000|kg|abbr=on}} are synthesized annually.<ref name=yarnell> {{cite journal |last=Yarnell |first=A. |title=The Many Facets of Man-Made Diamonds |url=http://pubs.acs.org/cen/coverstory/8205/8205diamonds.html |journal=[[Chemical and Engineering News]] |volume=82 |issue=5 |pages=26–31 |year=2004 }}</ref> Roughly 49% of diamonds originate from central and southern Africa, although significant sources of the mineral have been discovered in Canada, India, Russia, [[Brazil]], and Australia.<ref name=usgs/> They are mined from kimberlite and lamproite volcanic pipes, which can bring diamond crystals, originating from deep within the Earth where high pressures and temperatures enable them to form, to the surface. The mining and distribution of natural diamonds are subjects of frequent controversy such as with concerns over the sale of ''[[conflict diamond]]s'' or ''blood diamonds'' by African [[paramilitary]] groups.<ref name=conflict> {{cite web |title=Conflict Diamonds |url=http://www.un.org/peace/africa/Diamond.html |publisher=[[United Nations]] |date=2001-03-21 |accessdate=2009-05-05 }}</ref> The diamond supply chain is controlled by a limited number of powerful businesses, and is also highly concentrated in a small number of locations around the world (see figure). Only a very small fraction of the diamond ore consists of actual diamonds. The ore is crushed, during which care is required not to destroy larger diamonds, and then sorted by density. Today, diamonds are located in the diamond-rich density fraction with the help of [[X-ray fluorescence]], after which the final sorting steps are done by hand. Before the use of [[X-ray]]s became commonplace,<ref name=x50/> the separation was done with grease belts; diamonds have a stronger tendency to stick to grease than the other minerals in the ore.<ref name=harlow> {{cite book |last=Harlow |first=G.E. |title=The nature of diamonds |page=223;230-249 |url=http://books.google.com/books?id=_WI86J88ydAC&pg=PA223 |publisher=[[Cambridge University Press]] |year=1998 |isbn=0521629357 }}</ref> Historically diamonds were found only in alluvial deposits in [[southern India]].<ref name=Catelle1> {{cite book |last=Catelle |first=W.R. |title=The Diamond |publisher=John Lane Company |year=1911 |page=159}}</ref> India led the world in diamond production from the time of their discovery in approximately the 9th century BC<ref name=hershey/><ref name=Ball> {{cite book |last=Ball |first=V. |chapter=Chapter 1 |title=Diamonds, Gold and Coal of India |page=1 |publisher=Trübner & Co |location=London |year=1881 }} Ball was a geologist in British service.</ref> to the mid-18th century AD, but the commercial potential of these sources had been exhausted by the late 18th century and at that time India was eclipsed by Brazil where the first non-Indian diamonds were found in 1725.<ref name=hershey/> Diamond production of primary deposits (kimberlites and lamproites) only started in the 1870s after the discovery of the [[Diamond Fields]] in South Africa.<ref> {{cite book|title=Encyclopedia of African history|author=Shillington, K.|page=767|url=http://books.google.com/books?id=Ftz_gtO-pngC&pg=PA767|publisher=CRC Press|tear= 2005|isbn=1579584535|year=2005}} </ref> Production has increased over time and now an accumulated total of 4.5&nbsp;billion carats have been mined since that date.<ref name=giasummer2007> {{cite journal |last=Janse |first=A.J.A. |title=Global Rough Diamond Production Since 1870 |journal=Gems & Gemology |volume=43 |pages=98–119 |year=2007 |doi= }}</ref> Twenty percent of that amount has been mined in the last five years, and during the last 10 years, nine new mines have started production; four more are waiting to be opened soon. Most of these mines are located in Canada, Zimbabwe, Angola, and one in Russia.<ref name=giasummer2007/> In the U.S., diamonds have been found in [[Arkansas]], [[Colorado]], and [[Montana]].<ref name=DGemGLorenz> {{cite journal |last=Lorenz |first=V. |title=Argyle in Western Australia: The world's richest diamantiferous pipe; its past and future |journal=Gemmologie, Zeitschrift der Deutschen Gemmologischen Gesellschaft |volume=56 |issue=1–2 |pages=35–40 |year=2007 |doi= }}</ref><ref name=Montana> {{cite web |title=Microscopic diamond found in Montana |url=http://www.montanastandard.com/articles/2004/10/18/featuresbusiness/hjjfijicjbhdjc.txt |work=[[The Montana Standard]] |accessdate=2009-05-05 }}</ref> In 2004, the discovery of a microscopic diamond in the U.S. led to the January 2008 bulk-sampling of [[kimberlite pipes]] in a remote part of [[Montana]].<ref name=Montana/><ref> {{cite web |title=Apex Geoscience Completes Bulk Sampling, Submits Samples for Laboratory Testing |url=http://www.deltamine.com/release2008-01-08.htm |publisher=[[Delta Consolidated Mining Company|Delta Mining]] |date=2008 |accessdate=2008-11-03 }}</ref> Today, most commercially viable diamond deposits are in Russia (mostly in [[Sakha Republic]], for example [[Mir Mine|Mir pipe]] and [[Udachnaya pipe]]), [[Botswana]], Australia (Northern and Western Australia) and the [[Democratic Republic of Congo]].<ref> {{cite web |last=Marshall |first=S. |coauthors=Shore, J. |title=The Diamond Life |url=http://gnn.tv/videos/2/The_Diamond_Life |publisher=[[Guerrilla News Network]] |year=2004 |accessdate=2007-03-21 }}</ref> In 2005, Russia produced almost one-fifth of the global diamond output, reports the [[British Geological Survey]]. Australia boasts the richest diamantiferous pipe with production reaching peak levels of {{convert|42|MT}} per year in the 1990s.<ref name=DGemGLorenz/> There are also commercial deposits being actively mined in the [[Northwest Territories]] of Canada and [[Brazil]].<ref name=usgs/> Diamond prospectors continue to search the globe for diamond-bearing kimberlite and lamproite pipes. ===Controversial sources=== {{seealso|Blood diamond}} In some of the more politically unstable central African and west African countries, revolutionary groups have taken control of [[List of diamond mines|diamond mines]], using proceeds from diamond sales to finance their operations. Diamonds sold through this process are known as ''conflict diamonds'' or ''blood diamonds''.<ref name=conflict/> Major diamond trading corporations continue to fund and fuel these conflicts by doing business with armed groups. In response to public concerns that their diamond purchases were contributing to war and [[human rights abuses]] in [[central Africa|central]] and [[West Africa|western]] Africa, the [[United Nations]], the diamond industry and diamond-trading nations introduced the [[Kimberley Process]] in 2002.<ref name=kimb>{{cite book|url=http://books.google.com/books?id=hWrEcl2ydzEC&pg=PA305|pages=305-313|title=Resource politics in Sub-Saharan Africa|author=Basedau, M.; Mehler, A|year=2005|publisher=GIGA-Hamburg|isbn=3928049917}}</ref> The Kimberley Process aims to ensure that conflict diamonds do not become intermixed with the diamonds not controlled by such rebel groups. This is done by requiring diamond-producing countries to provide proof that the money they make from selling the diamonds is not used to fund criminal or revolutionary activities. Although the Kimberley Process has been moderately successful in limiting the number of conflict diamonds entering the market, some still find their way in. Conflict diamonds constitute 2–3% of all diamonds traded.<ref> {{cite web |title=World Federation of Diamond Bourses (WFDB) and International Diamond Manufacturers Association: Joint Resolution of 19 July 2000 |url=http://books.google.ca/books?id=fnRnyS7I9cYC&pg=PA334&lpg=PA334 |publisher=World Diamond Council |date=2000-07-19 |accessdate=2006-11-05 }}</ref> Two major flaws still hinder the effectiveness of the Kimberley Process: (1) the relative ease of smuggling diamonds across African borders, and (2) the violent nature of diamond mining in nations that are not in a technical state of war and whose diamonds are therefore considered "clean".<ref name=kimb/> The Canadian Government has set up a body known as Canadian Diamond Code of Conduct<ref> {{cite web |title=Voluntary Code of Conduct For Authenticating Canadian Diamond Claims |url=http://www.cb-bc.gc.ca/eic/site/cb-bc.nsf/vwapj/Code_EN_Jan_06_FINAL.pdf/$file/Code_EN_Jan_06_FINAL.pdf |publisher=Canadian Diamond Code Committee |year=2006 |accessdate=2007-10-30 |format=PDF }}</ref> to help authenticate Canadian diamonds. This is a stringent tracking system of diamonds and helps protect the "conflict free" label of Canadian diamonds.<ref> {{cite journal |last=Kjarsgaard |first=B.A. |last2=Levinson |first2=A.A. |title=Diamonds in Canada |journal=Gems and Gemology |volume=38 |issue=3 |pages=208–238 |year=2002 |doi= }}</ref> ==Commercial markets== {{See also|Diamonds as an investment}} [[Image:Diamond.jpg|framed|alt=A clear faceted gem supported in four clamps attached to a wedding ring|A round [[Brilliant (diamond cut)|brilliant cut]] diamond set in a ring]] The diamond industry can be separated into two basically distinct categories: one dealing with gem-grade diamonds and another for industrial-grade diamonds. While a large trade in both types of diamonds exists, the two markets act in dramatically different ways. ===Gemstones and their distribution=== {{Main|Diamond (gemstone)}} A large trade in [[Gemstone|gem]]-grade diamonds exists. Unlike other commodities, such as most precious metals, there is a substantial mark-up in the retail sale of gem diamonds.<ref>{{cite web|accessdate=2009-07-07|url=http://www.photius.com/diamonds/the_diamond_industry.html|title=The Diamond Industry}}</ref> There is a well-established market for resale of polished diamonds (e.g. pawnbroking, auctions, second-hand jewelry stores, diamantaires, bourses, etc.). One hallmark of the trade in gem-quality diamonds is its remarkable concentration: wholesale trade and [[diamond cutting]] is limited to just a few locations; In 2003, 92% of the world's diamonds were cut and polished in [[Surat]], [[India]].<ref> {{cite news |last=Adiga |first=A. |title=Uncommon Brilliance |url=http://www.time.com/time/magazine/article/0,9171,501040419-610100,00.html |work=[[Time (magazine)|Time]] |date=2004-04-12 |accessdate=2008-11-03 }}</ref> Other important centers of diamond cutting and trading are [[Antwerp]], where the [[International Gemological Institute]] is based, London, New York City, [[Tel Aviv]], and Amsterdam. A single company—[[De Beers]]—controls a significant proportion of the trade in diamonds.<ref name=debeers>{{cite book|url=http://books.google.com/books?id=xoztFMavGCcC&pg=PA305|page=305|title=Principles of microeconomics|author=Mankiw, N. G|publisher=Elsevier|year=1998|isbn=0030245028|quote=A classic example of monpoly that arises fron ownership of a key resource is DeBeers ... which controls about 80 percent of the world's production of diamonds}}</ref> They are based in [[Johannesburg]], South Africa and London, England. One contributory factor is the geological nature of diamond deposits: several large primary kimberlite-pipe mines each account for significant portions of market share (such as the [[Jwaneng diamond mine|Jwaneng mine]] in Botswana, which is a single large pit operated by De Beers that can produce between 12.5 to 15 million carats of diamonds per year<ref> {{cite web |title=Jwaneng |url=http://www.debeersgroup.com/Exploration-and-mining/Mining-operations/Jwaneng/ |publisher=[[De Beers]] |accessdate=2009-04-26 }}</ref>), whereas secondary alluvial diamond deposits tend to be fragmented amongst many different operators because they can be dispersed over many hundreds of square kilometers (e.g., alluvial deposits in Brazil). The production and distribution of diamonds is largely consolidated in the hands of a few key players, and concentrated in traditional diamond trading centers. The most important being Antwerp, where 80% of all rough diamonds, 50% of all cut diamonds and more than 50% of all rough, cut and industrial diamonds combined are handled.<ref name=india> {{cite book |last=Tichotsky |first=J. |title=Russia's Diamond Colony: The Republic of Sakha |url=http://books.google.com/books?id=F7N4G_wxkUYC |page=254 |publisher=[[Routledge]] |year=2000 |isbn=9057024209 }}</ref> This makes Antwerp a de facto "world diamond capital". Another important diamond center is New York City, where almost 80% of the world's diamonds are sold, including auction sales.<ref name=india/> The DeBeers company, as the world's largest diamond miner holds a dominant position in the industry, and has done so since soon after its founding in 1888 by the British imperialist [[Cecil Rhodes]]. De Beers owns or controls a significant portion of the world's rough diamond production facilities (mines) and [[Distribution (business)|distribution channels]] for gem-quality diamonds. The Diamond Trading Company (DTC) is a subsidiary of De Beers and markets rough diamonds from De Beers-operated mines. De Beers and its subsidiaries own mines that produce some 40% of annual world diamond production. For most of the 20th century over 80% of the world's rough diamonds passed through De Beers,<ref> {{cite web|url=http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:32003D0079:EN:HTML |title=Commission Decision of 25 July 2001 declaring a concentration to be compatible with the common market and the EEA Agreement|work=Case No COMP/M.2333 – De Beers/LVMH |publisher=[[EUR-Lex]]|year=2003}}</ref> but in the period 2001–2009 the figure has decreased to around 45%.<ref> {{cite journal |title=Business: Changing facets; Diamonds |url=http://pages.stern.nyu.edu/~lwhite/f&m.assignments.2008/f&m.presentationmaterials/DeBeers/Economist%20Feb-24-2007.pdf |journal=[[The Economist]] |volume=382 |issue=8517 |page=68 |year=2007}}</ref> De Beers sold off the vast majority its diamond stockpile in the late 1990s – early 2000s<ref>{{cite web |title=The Elusive Sparcle |url=http://www.gjepc.org/solitaire/magazines/Aug05_Sep05/aug05_sep05.aspx?inclpage=Specials&section_id=3 |publisher=The Gem & Jewellery Export Promotion Council |accessdate=2009-04-26 }}</ref> and the remainder largely represents working stock (diamonds that are being sorted before sale).<ref> {{cite news |last=Even-Zohar |first=C. |title=Crisis Mitigation at De Beers |url=http://www.namakwadiamonds.co.za/nd/uploads/wysiwyg/documents/081106_DIB.pdf |publisher=DIB online |date=2008-11-06 |accessdate=2009-04-26 |format=PDF }}</ref> This was well documented in the press<ref> {{ cite web |last=Even-Zohar |first=C. |title=De Beers to Halve Diamond Stockpile |url=http://www.allbusiness.com/retail-trade/apparel-accessory-stores-womens-specialty/4224156-1.html |publisher=National Jeweler |date=1999-11-03 |accessdate=2009-04-26 }}</ref> but remains little known to the general public. As a part of reducing its influence, De Beers withdrew from purchasing diamonds on the open market in 1999 and ceased, at the end of 2008, purchasing Russian diamonds mined by the largest Russian diamond company [[Alrosa]].<ref> {{cite web |title=Judgment of the Court of First Instance of 11 July 2007 – Alrosa v Commission |url=http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:C:2007:199:0037:01:EN:HTML |publiser=[[EUR-Lex]] |date=2007 |accessdate=2009-04-26 }}</ref> Alrosa however had to suspend their sales in October 2008 due to the [[2000s energy crisis|global energy crisis]] and is expected to resume them in autumn 2009.<ref> {{cite web |title=Diamond producer Alrosa to resume market diamond sales in May |url=http://en.rian.ru/business/20090506/121458087.html |publisher=[[RIA Novosti]] |date=2009-05-06 |accessdate=2009-05-25 }}</ref> Apart from Alrosa, other important diamond mining companies include [[BHP Billiton]], which is the world's largest mining company;<ref>{{cite news| url =http://www.abc.net.au/news/stories/2007/08/22/2012367.htm| title = Another record profit for BHP |publisher = ABC News|date = 2007-08-22|accessdate = 2007-08-23}}</ref> [[Rio Tinto Group]], the owner of Argyle (100%), [[Diavik Diamond Mine|Diavik]] (60%), and [[Murowa diamond mine|Murowa]] (78%) diamond mines;<ref name="RTCompanies">{{cite web| title = Our Companies| work = Rio Tinto web site| publisher = Rio Tinto| url = http://www.riotinto.com/whatweproduce/218_our_companies.asp| accessdate = 2009-03-05}}</ref> and [[Petra Diamonds]], the owner of several major diamond mines in Africa. Further down the supply chain, members of The [[World Federation of Diamond Bourses]] (WFDB) act as a medium for wholesale diamond exchange, trading both polished and rough diamonds. The WFDB consists of independent diamond bourses in major cutting centers such as Tel Aviv, Antwerp, Johannesburg and other cities across the USA, Europe and Asia.<ref name=harlow/> In 2000, the WFDB and The International Diamond Manufacturers Association established the [[World Diamond Council]] to prevent the trading of diamonds used to fund war and inhumane acts. WFDB's additional activities include sponsoring the [[World Diamond Congress]] every two years, as well as the establishment of the ''[[International Diamond Council]]'' (IDC) to oversee diamond grading. Once purchased by Sightholders (which is a trademark term referring to the companies that have a three-year supply contract with DTC), diamonds are cut and polished in preparation for sale as gemstones ('industrial' stones are regarded as a by-product of the gemstone market; they are used for abrasives).<ref name=polish>{{cite book|url=http://books.google.com/books?id=fkBJ0HL34WsC&pg=PA297|pages=297–299|title=Africa's silk road|author=Broadman, H. G.; Isik, G|publisher=World Bank Publications|year=2007|isbn=0821368354}}</ref> The cutting and polishing of rough diamonds is a specialized skill that is concentrated in a limited number of locations worldwide.<ref name=polish/> Traditional diamond cutting centers are Antwerp, [[Amsterdam]], [[Johannesburg]], New York City, and [[Tel Aviv]]. Recently, diamond cutting centers have been established in China, India, [[Thailand]], Namibia and Botswana.<ref name=polish/> Cutting centers with lower cost of labor, notably [[Surat]] in [[Gujarat|Gujarat, India]], handle a larger number of smaller carat diamonds, while smaller quantities of larger or more valuable diamonds are more likely to be handled in Europe or North America. The recent expansion of this industry in India, employing low cost labor, has allowed smaller diamonds to be prepared as gems in greater quantities than was previously economically feasible.<ref name=india/> Diamonds which have been prepared as gemstones are sold on diamond exchanges called ''bourses''. There are 26 registered diamond bourses in the world.<ref> {{cite web |title=Bourse listing |url=http://www.worldfed.com/website/boursedirectory.html |publisher=World Federation of Diamond Bourses |accessdate=2007-04-04 }}</ref> Bourses are the final tightly controlled step in the diamond supply chain; wholesalers and even retailers are able to buy relatively small lots of diamonds at the bourses, after which they are prepared for final sale to the consumer. Diamonds can be sold already set in jewelry, or sold unset ("loose"). According to the [[Rio Tinto Group]], in 2002 the diamonds produced and released to the market were valued at US$9&nbsp;billion as rough diamonds, US$14&nbsp;billion after being cut and polished, US$28&nbsp;billion in wholesale diamond jewelry, and US$57&nbsp;billion in retail sales.<ref> {{cite web |title=North America Diamond Sales Show No Sign of Slowing |url=http://www.awdiamonds.com/article-8.html |publisher=A&W diamonds |accessdate=2009-05-05 }}</ref> ====Marketing==== The image of diamond as a valuable commodity has been preserved through clever marketing campaigns. In particular, the [[De Beers#Marketing|De Beers diamond advertising campaign]] is acknowledged as one of the most successful and innovative campaigns in history. [[N. W. Ayer & Son]], the advertising firm retained by De Beers in the mid-20th century, succeeded in reviving the American diamond market and opened up new markets, even in countries where no diamond tradition had existed before. N. W. Ayer's multifaceted marketing campaign included [[product placement]], advertising the diamond itself rather than the De Beers brand, and building associations with celebrities and royalty. This coordinated campaign has lasted decades and continues today; it is perhaps best captured by the slogan "a diamond is forever".<ref name=sell> {{cite web |last=Epstein |first=E.J. |title=Have You Ever Tried To Sell a Diamond? |url=http://www.theatlantic.com/issues/82feb/8202diamond1.htm |work=[[The Atlantic]] |date=1982 |accessdate=2009-05-05 }}</ref> Another example of successful diamond marketing is brown Australian diamonds. Brown-colored diamonds have always constituted a significant part of the diamond production. However they were considered worthless for jewelry; they were not even assessed on the [[diamond color]] scale, and were predominantly used for industrial purposes. However, the attitude has changed drastically after the development of [[Argyle diamond mine]] in Australia in 1986. As a result of an aggressive marketing campaign, the brown diamonds have become acceptable gems.<ref>{{cite book|url=http://books.google.com/books?id=_WI86J88ydAC&pg=PA34|page=34|title=The nature of diamonds|author=George E. Harlow|publisher=Cambridge University Press|year=1998|isbn=0521629357}}</ref><ref>{{cite book|url=http://books.google.com/books?id=zNicdkuulE4C&pg=PA416|page=416|title=Industrial minerals & rocks|author=Jessica Elzea Kogel|publisher= Society for Mining, Metallurgy, and Exploration (U.S.)|year=2006|isbn=0873352335}}</ref>. The change was mostly due to the numbers: the Argyle mine, with its 35 million carats (7,000&nbsp;kg) of diamonds per year, makes about one-third of global production of natural diamonds;<ref>{{cite web|accessdate=2009-08-04|url=http://www.costellos.com.au/diamonds/industry.html|title=The Australian Diamond Industry}}</ref> 80% of Argyle diamonds are brown.<ref>{{cite book|url=http://books.google.com/books?id=068-M3xrDSQC&pg=PT158|page=158|title=}}</ref> ====Cutting==== {{main|Diamond cutting|Diamond cut}} [[Image:Darya-e Noor Diamond of Iran.png|thumb|right|alt=A large rectangular pink multifaceted gemstone, set in a decorative surround. The decoration includes a row of small clear faceted gemstones around the main gem's perimeter, and clusters of gems forming a crest on one side. The crest comprises a three-pointed crown faced by two unidentifiable animals.|The [[Darya-ye Noor|Darya-I-Nur]] Diamond—an example of unusual diamond cut and jewelry arrangement]] The mined rough diamonds are converted into gems through a multi-step process called "cutting". Diamonds are extremely hard, but also brittle and can be split up by a single blow. Therefore, the diamond cutting is traditionally considered as a delicate procedure requiring skills, scientific knowledge, tools and experience. Its final goal is to produce a facetted jewel where the specific angles between the facets would optimize the diamond luster, that is dispersion of white light, whereas the number and area of facets would determine the weight of the final product. The weight reduction upon cutting is significant and can be of the order of 50%.<ref name=x50>{{cite book|url=http://books.google.com/books?id=jPT6JADCqgwC&pg=PA280|page=280|title=Handbook of carbon, graphite, diamond, and fullerenes: properties, processing, and applications|author=Pierson,Hugh O|publisher=William Andrew|year=1993|isbn=0815513399}}</ref> Several possible shapes are considered, but the final decision is often determined not only by scientific, but also practical considerations. For example the diamond might be intended for display or for wear, in a ring or a necklace, singled or surrounded by other gems of certain color and shape.<ref name=antique>{{cite book|url=http://books.google.com/books?id=Y84qRt6nz-8C&pg=PA88|pages=82-102|title=Antique jewellery: its manufacture, materials and design|author=James, Duncan S|publisher=Osprey Publishing|year=1998|isbn=0747803854}}</ref> The most time-consuming part of the cutting is the preliminary analysis of the rough stone. It needs to address a large number of issues, bears much responsibility, and therefore can last years in case of unique diamonds. The following issues are being considered: *The hardness of diamond and its ability to cleave strongly depend on the crystal orientation. Therefore, the crystallographic structure of the diamond to be cut is analyzed using [[X-ray diffraction]] in order to choose the optimal cutting directions. *Most diamonds contain visible non-diamond inclusions and crystal flaws. The cutter has to decide which flaws are to be removed by the cutting and which could be kept. *The diamond can be split by a single, well calculated blow of a hammer to a pointed tool, which is quick, but risky. Alternatively, it can be cut with a [[diamond saw]], which is a more reliable but tedious procedure.<ref name=antique/><ref>{{cite book|url=http://books.google.com/books?id=X3qe9jzYUAQC&pg=PA984|pages=984-992|title=Handbook of industrial diamonds and diamond films|author=Prelas, Mark Antonio; Popovici, Galina; Bigelow,Louis K.|publisher=CRC Press|year=1998|isbn=0824799941}}</ref> After initial cutting, the diamond is shaped in numerous stages of polishing. Contrary to cutting, which is a responsible but quick operation, polishing removes material by gradual erosion and is extremely time consuming. However the associated technique is well developed; it is considered as a routine and can be performed by technicians.<ref>{{cite journal|url=http://books.google.com/books?id=i9kDAAAAMBAJ&pg=PA760|pages=760-764|title=Popular Mechanics|year=1940|volume=74|issue=5|issn=0032-4558|publisher=Hearst Magazines}}</ref> After polishing, the diamond is reexamined for possible flaws, either remaining or induced by the process. Those flaws are concealed through various [[diamond enhancement]] techniques, such as repolishing, crack filling, or clever arrangement of the stone in the jewelry. Remaining non-diamond inclusions are removed through laser drilling and filling of the produced voids.<ref name=read>{{cite book|url=http://books.google.com/books?id=t-OQO3Wk-JsC&pg=PA166|pages=165-166|title=Gemmology|author=Read, P. G.|publisher=Butterworth-Heinemann|year= 2005|isbn=0750664495}}</ref> ===Industrial uses=== [[Image:Dia scalpel.jpg|thumb|180 px|alt=A diamond scalpel consisting of a yellow diamond blade attached to a pen-shaped holder|A [[scalpel]] with synthetic diamond blade]] [[File:Diamond blade very macro.jpg|thumb|alt=A polished metal slab embedded with small diamonds|Diamonds in an [[angle grinder]] blade]] The market for industrial-grade diamonds operates much differently from its gem-grade counterpart. Industrial diamonds are valued mostly for their hardness and heat conductivity, making many of the gemological characteristics of diamonds, such as clarity and color, irrelevant for most applications. This helps explain why 80% of mined diamonds (equal to about 135&nbsp;million carats or 27&nbsp;[[Tonne|metric tons]] annually), unsuitable for use as gemstones, are destined for industrial use. In addition to mined diamonds, synthetic diamonds found industrial applications almost immediately after their invention in the 1950s; another 570&nbsp;million carats (114&nbsp;tons) of synthetic diamond is produced annually for industrial use. Approximately 90% of diamond grinding grit is currently of synthetic origin.<ref name=usgs> {{cite web |title=Industrial Diamonds Statistics and Information |url=http://minerals.usgs.gov/minerals/pubs/commodity/diamond/ |work=[[United States Geological Survey]] |accessdate=2009-05-05 }}</ref> The boundary between gem-quality diamonds and industrial diamonds is poorly defined and partly depends on market conditions (for example, if demand for polished diamonds is high, some suitable stones will be polished into low-quality or small gemstones rather than being sold for industrial use). Within the category of industrial diamonds, there is a sub-category comprising the lowest-quality, mostly opaque stones, which are known as ''[[bort]]''.<ref name=spear> {{cite book |last=Spear|first=K.E |last2=Dismukes |first2=J.P. |title=Synthetic Diamond: Emerging CVD Science and Technology |url=http://books.google.com/books?id=RR5HF25DB7UC |page=628 |publisher=[[John Wiley & Sons|Wiley]]–[[IEEE]] |year=1994 |isbn=0471535893 }}</ref> Industrial use of diamonds has historically been associated with their hardness; this property makes diamond the ideal material for cutting and grinding tools. As the hardest known naturally occurring material, diamond can be used to polish, cut, or wear away any material, including other diamonds. Common industrial adaptations of this ability include diamond-tipped [[drill bit]]s and saws, and the use of diamond powder as an [[abrasive]]. Less expensive industrial-grade diamonds, known as [[bort]], with more flaws and poorer color than gems, are used for such purposes.<ref> {{cite book |last=Holtzapffel |first=C. |title=Turning And Mechanical Manipulation |url=http://books.google.com/books?id=omwPAAAAYAAJ&pg=PA178 |publisher=Holtzapffel & Co |pages=176–178 |year=1856 }}</ref> Diamond is however not suitable for machining [[ferrous]] [[alloy]]s at high speeds, as carbon is soluble in iron at the high temperatures created by high-speed machining, leading to greatly increased wear on diamond tools when compared to alternatives.<ref> {{cite journal |last=Coelho |first=R.T. |last2=Yamada |first2=S. |last3=Aspinwall |first3=D.K. |last4=Wise |first4=M.L.H. |title=The application of polycrystalline diamond (PCD) tool materials when drilling and reaming aluminum-based alloys including MMC |journal=International Journal of Machine Tools and Manufacture |volume=35 |issue=5 |pages=761–774 |year=1995 |doi=10.1016/0890-6955(95)93044-7 }}</ref> Specialized applications include use in laboratories as containment for [[Pressure experiment|high pressure experiments]] (see [[diamond anvil cell]]), high-performance [[bearing (mechanical)|bearings]], and limited use in specialized [[window]]s.<ref name=spear/> With the continuing advances being made in the production of synthetic diamonds, future applications are becoming feasible. Garnering much excitement is the possible use of diamond as a [[semiconductor]] suitable to build [[integrated circuit|microchip]]s from, or the use of diamond as a [[heat sink]]<ref> {{cite journal |last=Sakamoto |first=M. |coauthors=''et al.'' |title=120&nbsp;W CW output power from monolithic AlGaAs (800&nbsp;nm) laser diode array mounted on diamond heatsink |journal=[[Electronics Letters]] |volume=28 |issue=2 |pages=197–199 |year=1992 |doi=10.1049/el:19920123 }}</ref> in electronics. ==Synthetics, simulants, and enhancements== ===Synthetics=== {{Main|Synthetic diamond}} [[Image:HPHTdiamonds2.JPG|thumb|alt=Six crystals of cubo-octahedral shapes, each about 2 millimeters in diameter. Two are pale blue, one is pale yellow, one is gree-blue, one is dark blue and one green-yellow.|Synthetic diamonds of various colors grown by the high-pressure high-temperature technique]] Synthetic diamonds are diamond crystals that are manufactured in a laboratory, as opposed to natural diamonds which form naturally within the Earth. The gemological and industrial uses of diamond have created a large demand for rough stones. This demand has been satisfied in large part by synthetic diamonds, which have been manufactured by various processes for more than half a century. However, in recent years it has become possible to produce gem-quality synthetic diamonds of significant size.<ref name="AMNH"/> The majority of commercially available synthetic diamonds are yellow in color and produced by so called High Pressure High Temperature ([[HPHT]]) processes.<ref>{{cite journal |last=Shigley |first=J.E. |coauthors=''et al.'' |title=Gemesis Laboratory Created Diamonds |journal=Gems & Gemology |volume=38 |issue=4 |pages=301–309 |year=2002 |doi= }}</ref> The yellow color is caused by nitrogen impurities. Other colors may also be reproduced such as blue, green or pink, which are a result of the addition of boron or from irradiation after synthesis.<ref> {{cite journal |last=Shigley |first=J.E. |coauthors=''et al.'' |title=Lab Grown Colored Diamonds from Chatham Created Gems |journal=Gems & Gemology |volume=40 |issue=2 |pages=128–145 |year=2004 |doi= }}</ref> [[Image:Apollo synthetic diamond.jpg|thumb|right|alt=A round, clear gemstone with many facets, the main face being hexagonal, surrounded by many smaller facets.|Colorless gem cut from diamond grown by chemical vapor deposition]] Another popular method of growing synthetic diamond is chemical vapor deposition (CVD). The growth occurs under low pressure (below atmospheric pressure). It involves feeding a mixture of gases (typically 1 to 99 [[methane]] to [[hydrogen]]) into a chamber and splitting them to chemically active [[Radical (chemistry)|radicals]] in a [[Plasma (physics)|plasma]] ignited by [[microwaves]], [[hot filament]], [[Electric arc|arc discharge]], [[welding torch]] or [[laser]].<ref name=CVD> {{cite journal |last=Werner |first=M. |coauthors=''et al.'' |title=Growth and application of undoped and doped diamond films |journal=Reports on Progress in Physics |volume=61 |page=1665 |year=1998 |doi=10.1088/0034-4885/61/12/002 }}</ref> This method is mostly used for coatings, but can also produce single crystals several millimeters in size (see picture).<ref name=yarnell/> At present, the annual production of gem quality synthetic diamonds is only a few thousand carats, whereas the total production of natural diamonds is around 120&nbsp;million carats. Despite this fact, a purchaser is more likely to encounter a synthetic when looking for a fancy-colored diamond because nearly all synthetic diamonds are fancy-colored, while only 0.01% of natural diamonds are fancy-colored.<ref>{{cite book|url=http://books.google.com/books?id=zNicdkuulE4C&pg=PA428|pages=426–430|title=Industrial Minerals & Rocks|author=Kogel, J. E.|publisher=SME| year= 2006|isbn=0873352335}}</ref> ===Simulants=== {{Main|Diamond simulant}} [[Image:MoissaniteRoundJewel.jpg|thumb|alt=A round sparkling, clear gemstone with many facets.|Gem-cut synthetic silicon carbide]] A [[diamond simulant]] is defined as a non-diamond material that is used to simulate the appearance of a diamond. Diamond-simulant gems are often referred to as diamante. The most familiar diamond simulant to most consumers is [[cubic zirconia]]. The popular gemstone [[moissanite]] (silicon carbide) is often treated as a diamond simulant, although it is a gemstone in its own right. While moissanite does look similar to diamond, its main disadvantage as a diamond simulant is that cubic zirconia is far cheaper and arguably equally convincing. Both cubic zirconia and moissanite are produced synthetically.<ref> {{cite book |last=O'Donoghue |first=M. |last2=Joyner |first2=L. |title=Identification of gemstones |pages=12–19 |publisher=Butterworth-Heinemann |location=Great Britain |year=2003 |isbn=0750655127 }}</ref> ===Enhancements=== {{Main|Diamond enhancement}} Diamond enhancements are specific treatments performed on natural or synthetic diamonds (usually those already cut and polished into a gem), which are designed to better the gemological characteristics of the stone in one or more ways. These include laser drilling to remove inclusions, application of sealants to fill cracks, treatments to improve a white diamond's color grade, and treatments to give fancy color to a white diamond.<ref>{{cite book|url=http://books.google.com/books?id=kCc80Q4gzSgC&pg=PA115|page=115|title=The diamond formula|author=Barnard, A. S|publisher=Butterworth-Heinemann|year=2000|isbn=0750642440}}</ref> Coatings are increasingly used to give a diamond simulant such as cubic zirconia a more "diamond-like" appearance. One such substance is [[diamond-like carbon]]—an amorphous carbonaceous material that has some physical properties similar to those of the diamond. Advertising suggests that such a coating would transfer some of these diamond-like properties to the coated stone, hence enhancing the diamond simulant. However, modern techniques such as [[Raman spectroscopy|Raman Spectroscopy]] should easily identify such a treatment.<ref> {{cite journal |last= Shigley |first=J.E. |title=Observations on new coated gemstones |journal=Gemmologie: Zeitschrift der Deutschen Gemmologischen Gesellschaft |volume=56 |issue=1–2 |pages=53–56 |year=2007 }}</ref> ===Identification=== Early diamond identification tests included a scratch test relying on the superior hardness of diamond. This test is however destructive, as a diamond can scratch diamond, and is rarely used nowadays. Instead, diamond identification relies on its superior thermal conductivity. Electronic thermal probes are widely used in the gemological centers to separate diamonds from their imitations. These probes consist of a pair of battery-powered [[thermistor]]s mounted in a fine copper tip. One thermistor functions as a heating device while the other measures the temperature of the copper tip: if the stone being tested is a diamond, it will conduct the tip's thermal energy rapidly enough to produce a measurable temperature drop. This test takes about 2&ndash;3 seconds.<ref>J. F. Wenckus "Method and means of rapidly distinguishing a simulated diamond from natural diamond" {{US patent|4488821}} December 18, 1984</ref> Whereas the thermal probe can separate diamonds from most of their simulants, distinguishing between various types of diamond, for example synthetic or natural, irradiated or non-irradiated, etc., requires more advanced, optical techniques. Those techniques are also used for some diamonds simulants, such as [[silicon carbide]], which pass the thermal conductivity test. Optical techniques can distinguish between natural diamonds and synthetic diamonds. They can also identify the vast majority of treated natural diamonds.<ref name=raman>{{cite book|url=http://books.google.com/books?id=W2cSkEsWbSkC&pg=PA387|pages=387–394|title=Raman spectroscopy in archaeology and art history|author=Edwards, H. G. M. and Chalmers, G. M|publisher=Royal Society of Chemistry|year=2005|isbn=0854045228}}</ref> "Perfect" crystals (at the atomic lattice level) have never been found, so both natural and synthetic diamonds always possess characteristic imperfections, arising from the circumstances of their crystal growth, that allow them to be distinguished from each other.<ref name=spot/> Laboratories use techniques such as spectroscopy, microscopy and luminescence under shortwave ultraviolet light to determine a diamond's origin.<ref name=raman/> They also use specially made machines to aid them in the identification process. Two screening machines are the ''DiamondSure'' and the ''DiamondView'', both produced by the [[Diamond Trading Company|DTC]] and marketed by the [[Gemological Institute of America|GIA]].<ref> {{cite web |last=Donahue |first=P.J. |title=DTC Appoints GIA Distributor of DiamondSure and DiamondView |url=http://www.professionaljeweler.com/archives/news/2004/041904story.html |work=Professional Jeweler Magazine |date=2004-04-19 |accessdate=2009-03-02 }}</ref> Several methods for identifying synthetic diamonds can be performed, depending on the method of production and the color of the diamond. [[Chemical vapor deposition|CVD]] diamonds can usually be identified by an orange fluorescence. D-J colored diamonds can be screened through the [[Swiss Gemmological Institute]]'s<ref> {{cite web |title=SSEF diamond spotter and SSEF illuminator |url=http://dkamhi.com/ssef%20type%20IIa.htm |publisher=SSEF Swiss Gemmological Institute |accessdate=2009-05-05 }}</ref> Diamond Spotter. Stones in the D-Z color range can be examined through the DiamondSure UV/visible spectrometer, a tool developed by De Beers.<ref name=spot> {{cite journal |last=Welbourn |first=C. |title=Identification of Synthetic Diamonds: Present Status and Future Developments<!--Proceedings of the 4th International Gemological Symposium--> |journal=Gems & Gemology |volume=42 |issue=3 |pages=34–35 |year=2006}}</ref> Similarly, natural diamonds usually have minor imperfections and flaws, such as inclusions of foreign material, that are not seen in synthetic diamonds. ==See also== {{portalpar|Gemology and Jewelry|AEW diamond solo white.gif|35}} *[[Diamond drilling]] *[[List of famous diamonds]] *[[List of minerals]] *[[Diamonds as an investment]] ==References== {{reflist|2}} ==Books== *{{cite book|author=C. Even-Zohar|year=2007|title=From Mine to Mistress: Corporate Strategies and Government Policies in the International Diamond Industry|edition=2nd|publisher=Mining Journal Press|url=http://www.mine2mistress.com|isbn=}} *{{cite book|author=G. Davies|year=1994|title=Properties and growth of diamond|publisher=INSPEC|isbn=0852968752}} *{{cite book|author =M. O'Donoghue, M|title=Gems|publisher=Elsevier|year=2006|isbn=0750658568}} *{{cite book|author=M. O'Donoghue and L. Joyner|year=2003|title=Identification of gemstones|publisher=Butterworth-Heinemann|location=Great Britain|isbn=0750655127}} *{{cite book|author=A. Feldman and L.H. Robins|year=1991|title=Applications of Diamond Films and Related Materials|publisher=Elsevier|isbn=}} *{{cite book|author=J.E. Field|year=1979|title=The Properties of Diamond|publisher=Academic Press|location=London|isbn=0122553500}} *{{cite book|author=J.E. Field|year=1992|title=The Properties of Natural and Synthetic Diamond|publisher=Academic Press|location=London|isbn=0122553527}} *{{cite book|author=W. Hershey|year=1940|title=The Book of Diamonds|publisher=Hearthside Press New York|url=http://books.google.com/books?id=35eij1e1al8C&printsec=frontcover|isbn =1417977159}} *{{cite book|author=S. Koizumi, C.E. Nebel and M. Nesladek|year=2008|title=Physics and Applications of CVD Diamond|publisher=Wiley VCH|isbn=3527408010|url =http://books.google.com/books?id=pRFUZdHb688C}} *{{cite book|author=L.S. Pan and D.R. Kani|year=1995|title=Diamond: Electronic Properties and Applications|publisher=Kluwer Academic Publishers|url=http://books.google.com/books?id=ZtfFEoXkU8wC&pg=PP1|isbn=0792395247}} *{{cite book|author=Pagel-Theisen, Verena|year=2001|title=Diamond Grading ABC: the Manual|publisher=Rubin & Son|location=Antwerp|isbn=3980043460}} *{{cite book|author=R.L. Radovic, P.M. Walker and P.A. Thrower|year=1965|title=Chemistry and physics of carbon: a series of advances|publisher=Marcel Dekker|location=New York|isbn=082470987X}} *{{cite book|author=M. Tolkowsky|year=1919|title= Diamond Design: A Study of the Reflection and Refraction of Light in a Diamond|publisher=E. & F.N. Spon|location=London|url=http://www.folds.net/diamond/index.html|isbn=}} *{{cite book|author=R.W. Wise|year=2003|title=Secrets Of The Gem Trade, The Connoisseur's Guide To Precious Gemstones|publisher=Brunswick House Pres|url=http://www.secretsofthegemtrade.com|isbn =}} *{{cite book|author=A.M. Zaitsev|year=2001|title=Optical Properties of Diamond: A Data Handbook|publisher=Springer|url=http://books.google.com/books?id=msU4jkdCEhIC&pg=PP1|isbn =354066582X}} ==External links== {{commons|Diamond}} {{Wiktionary}} * [http://www.ioffe.ru/SVA/NSM/Semicond/Diamond/index.html Properties of diamond: Ioffe database] * [http://newton.ex.ac.uk/people/sque/diamond/structure/structure.html Interactive structure of bulk diamond] (Java applet) * [http://www.pbs.org/wnet/nature/diamonds/index.html PBS Nature: Diamonds] * [http://www.mnh.si.edu/exhibits/si-gems Smithsonian's Splendour of Diamonds exhibit] * Epstein, Edward Jay (1982). [http://edwardjayepstein.com/diamond/prologue.htm ''The diamond invention''] (Complete book, includes "Chapter 20: [http://www.theatlantic.com/doc/198202/diamond Have you ever tried to sell a diamond?]" ) * [http://lgdl.gia.edu/pdfs/W97_fluoresce.pdf "A Contribution to the Understanding of Blue Fluorescence on the Appearance of Diamonds"]. (2007) [[Gemological Institute of America|Gemological_Institute_of_America (GIA)]] * Tyson, Peter (November 2000). [http://www.pbs.org/wgbh/nova/diamond/sky.html "Diamonds in the Sky"]. Retrieved March 10, 2005. *[[Human Rights Watch]] [[Child Labor]] News[http://www.hrw.org/en/category/topic/children%E2%80%99s-rights/labor] and Report [http://www.hrw.org/en/reports/2009/06/26/diamonds-rough-0] <!--spacing, please do not remove--> {{Allotropes of carbon}} {{Jewellery}} [[Category:Diamond| ]] [[Category:Native element minerals]] [[Category:Impact event minerals]] [[Category:Economic geology]] [[Category:Semiconductor materials]] [[Category:Carbon]] [[Category:Transparent materials]] [[Category:Superhard materials]] [[Category:Abrasives]] [[Category:Greek loanwords]] {{Link FA|hu}} {{Link FA|lv}} {{Link FA|eo}} <!--Interlanguage links--> [[af:Diamant]] [[ar:ألماس]] [[an:Diamant]] [[az:Almaz]] [[zh-min-nan:Soān-chio̍h]] [[be:Алмаз]] [[be-x-old:Алмаз]] [[bs:Dijamant]] [[bg:Диамант]] [[ca:Diamant]] [[cs:Diamant]] [[cy:Diemwnt]] [[da:Diamant]] [[de:Diamant]] [[et:Teemant]] [[el:Διαμάντι]] [[es:Diamante]] [[eo:Diamanto]] [[eu:Diamante]] [[fa:الماس]] [[fo:Diamantar]] [[fr:Diamant]] [[gl:Diamante]] [[hak:Tson-sa̍k]] [[ko:다이아몬드]] [[hy:Ադամանդ]] [[hi:हीरा]] [[hr:Dijamant]] [[io:Diamanto]] [[bpy:ডিয়ামান্টে]] [[id:Intan]] [[ia:Diamante]] [[is:Demantur]] [[it:Diamante]] [[he:יהלום]] [[kn:ವಜ್ರ]] [[ka:ბრილიანტი]] [[sw:Almasi]] [[la:Adamas]] [[lv:Dimants]] [[lt:Deimantas]] [[li:Diamaant]] [[jbo:krilytabno]] [[lmo:Diamant]] [[hu:Gyémánt]] [[mk:Дијамант]] [[ml:വജ്രം (നവരത്നം)]] [[mr:हिरा]] [[ms:Berlian]] [[mwl:Diamante]] [[mn:Алмааз]] [[nl:Diamant]] [[ja:ダイヤモンド]] [[no:Diamant]] [[nn:Diamant]] [[pl:Diament]] [[pt:Diamante]] [[ro:Diamant]] [[qu:Q'ispi umiña]] [[ru:Алмаз]] [[sah:Алмаас]] [[sq:Diamanti]] [[simple:Diamond]] [[sk:Diamant]] [[sl:Diamant]] [[sr:Дијамант]] [[sh:Dijamant]] [[fi:Timantti]] [[sv:Diamant]] [[tl:Diyamante]] [[ta:வைரம்]] [[te:వజ్రం]] [[th:เพชร]] [[tg:Алмос]] [[tr:Elmas]] [[uk:Алмаз]] [[vi:Kim cương]] [[war:Diamante]] [[yi:בריליאנט]] [[yo:Díámọ̀ndì]] [[zh-yue:鑽石]] [[zh:钻石]]'
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