Editing Diamond (section)

== Synthetics, simulants, and enhancements ==
=== Synthetics ===
{{Main|Synthetic diamond}}

Synthetic diamonds are diamonds manufactured in a laboratory, as opposed to diamonds mined from 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"/> It is possible to make colorless synthetic gemstones that, on a molecular level, are identical to natural stones and so visually similar that only a gemologist with special equipment can tell the difference.<ref name="bain">{{cite web |url=http://www.bain.com/Images/PR_BAIN_REPORT_The_global_diamond_industry.pdf |archive-url=https://web.archive.org/web/20120131062348/http://www.bain.com/Images/PR_BAIN_REPORT_The_global_diamond_industry.pdf |archive-date=January 31, 2012 |url-status=live|title=The Global Diamond Industry: Lifting the Veil of Mystery|publisher=[[Bain and Company|Bain & Company]]|access-date=January 14, 2012}}</ref>

The majority of commercially available synthetic diamonds are yellow and are produced by so-called ''high-pressure high-temperature'' ([[HPHT]]) processes.<ref>{{cite journal| vauthors = Shigley JE, Abbaschian R |title=Gemesis Laboratory Created Diamonds|journal=Gems & Gemology|volume=38|issue=4|pages=301–309|year=2002|doi=10.5741/GEMS.38.4.301|doi-access=free|bibcode=2002GemG...38..301S }}</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 [[Gemstone irradiation|irradiation]] after synthesis.<ref>{{cite journal| vauthors = Shigley JE, Shen AH, Breeding CM, McClure SF, Shigley JE |title=Lab Grown Colored Diamonds from Chatham Created Gems|journal=Gems & Gemology|volume=40|issue=2|pages=128–145|year=2004|doi=10.5741/GEMS.40.2.128|doi-access=free|bibcode=2004GemG...40..128S }}</ref>

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 {{nowrap|1 to 99 [[methane]]}} to [[hydrogen]]) into a chamber and splitting them into chemically active [[radical (chemistry)|radicals]] in a [[plasma (physics)|plasma]] ignited by [[microwaves]], [[hot filament]], [[electric arc|arc discharge]], [[welding torch]], or [[laser]].<ref>{{cite journal | vauthors = Werner M, Locher R  |title=Growth and application of undoped and doped diamond films |journal=Reports on Progress in Physics |volume=61 |pages=1665–1710 |year=1998 |doi=10.1088/0034-4885/61/12/002 |issue=12 |bibcode=1998RPPh...61.1665W|s2cid=250878100 }}</ref> This method is mostly used for coatings, but can also produce single crystals several millimeters in size (see picture).<ref name=yarnell/>

As of 2010, nearly all 5,000&nbsp;million carats (1,000{{nbsp}}tonnes) of synthetic diamonds produced per year are for industrial use. Around 50% of the 133&nbsp;million carats of natural diamonds mined per year end up in industrial use.<ref name="bain"/><ref>{{cite web|url=https://www.cnbc.com/2012/08/27/the-billion-dollar-business-of-diamonds-from-mining-to-retail.html|vauthors=Pisani B|title=The Business of Diamonds, From Mining to Retail|publisher=[[CNBC]]|date=August 27, 2012|access-date=September 9, 2017|archive-date=July 7, 2017|archive-url=https://web.archive.org/web/20170707001321/http://www.cnbc.com/id/48782968|url-status=live}}</ref> Mining companies' expenses average 40 to 60&nbsp;US dollars per carat for natural colorless diamonds, while synthetic manufacturers' expenses average {{nowrap|$2,500 per carat}} for synthetic, gem-quality colorless diamonds.<ref name="bain"/>{{rp|79}} However, a purchaser is more likely to encounter a synthetic when looking for a fancy-colored diamond because only 0.01% of natural diamonds are fancy-colored, while most synthetic diamonds are colored in some way.<ref>{{cite book|url=https://books.google.com/books?id=zNicdkuulE4C&pg=PA428|pages=426–430|title=Industrial Minerals & Rocks|vauthors=Kogel JE|publisher=SME|year=2006|isbn=978-0-87335-233-8|access-date=November 9, 2020|archive-date=November 9, 2023|archive-url=https://web.archive.org/web/20231109173917/https://books.google.com/books?id=zNicdkuulE4C&pg=PA428#v=onepage&q&f=false|url-status=live}}</ref>

<gallery widths="200px" heights="180px">
File:HPHTdiamonds2.JPG|alt=Six crystals of cubo-octahedral shapes, each about 2 millimeters in diameter. Two are pale blue, one is pale yellow, one is green-blue, one is dark blue and one green-yellow.|Synthetic diamonds of various colors grown by the high-pressure high-temperature technique
File:Apollo synthetic diamond.jpg|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
</gallery>

=== Simulants ===
{{Main|Diamond simulant}}
[[File:Moissanite ring.JPG|thumb|alt=A round sparkling, clear gemstone with many facets.|Gem-cut synthetic silicon carbide set in a ring]]

A diamond simulant is a non-diamond material that is used to simulate the appearance of a diamond, and may be referred to as diamante. [[Cubic zirconia]] is the most common. The gemstone [[moissanite]] ([[silicon carbide]]) can be treated as a diamond simulant, though more costly to produce than cubic zirconia. Both are produced synthetically.<ref>{{cite book| vauthors = O'Donoghue M, Joyner L |title=Identification of gemstones|pages=12–19|publisher=Butterworth-Heinemann|location=Great Britain|year=2003|isbn=978-0-7506-5512-5}}</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=https://books.google.com/books?id=kCc80Q4gzSgC&pg=PA115|page=115|title=The diamond formula|vauthors=Barnard AS|publisher=Butterworth-Heinemann|year=2000|isbn=978-0-7506-4244-6|access-date=November 9, 2020|archive-date=November 9, 2023|archive-url=https://web.archive.org/web/20231109173812/https://books.google.com/books?id=kCc80Q4gzSgC&pg=PA115#v=onepage&q&f=false|url-status=live}}</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. Techniques such as [[Raman spectroscopy]] should easily identify such a treatment.<ref>{{cite journal| vauthors = Shigley JE |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 ===
[[File:Diamond (side view).png|thumb|[[Cathodoluminescence]] image of a diamond, taken in a [[scanning electron microscope]]]]
Early diamond identification tests included a scratch test relying on the superior hardness of diamond. This test is destructive, as a diamond can scratch another 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 two to three seconds.<ref>{{cite patent | inventor = Wenckus JF | country = US | number = 4488821 | title = Method and means of rapidly distinguishing a simulated diamond from natural diamond | pubdate = December 18, 1984 | fdate = November 24, 1982 | pridate = 1981-03-03 | assign1 = Ceres Electronics Corporation }}; {{US patent|4488821}}</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=https://books.google.com/books?id=W2cSkEsWbSkC&pg=PA387|pages=387–394|title=Raman spectroscopy in archaeology and art history|vauthors=Edwards HG, Chalmers GM|publisher=Royal Society of Chemistry|year=2005|isbn=978-0-85404-522-8|access-date=November 9, 2020|archive-date=November 9, 2023|archive-url=https://web.archive.org/web/20231109174417/https://books.google.com/books?id=W2cSkEsWbSkC&pg=PA387#v=onepage&q&f=false|url-status=live}}</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 instruments to aid them in the identification process. Two screening instruments are the ''DiamondSure'' and the ''DiamondView'', both produced by the [[Diamond Trading Company|DTC]] and marketed by the GIA.<ref>{{cite web |vauthors=Donahue PJ |title=DTC Appoints GIA Distributor of DiamondSure and DiamondView |url=http://www.professionaljeweler.com/archives/news/2004/041904story.html |work=Professional Jeweler Magazine |date=April 19, 2004 |access-date=March 2, 2009 |archive-date=March 6, 2012 |archive-url=https://web.archive.org/web/20120306220856/http://www.professionaljeweler.com/archives/news/2004/041904story.html |url-status=dead }}</ref>

Several methods for identifying synthetic diamonds can be performed, depending on the method of production and the color of the diamond. 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|access-date=May 5, 2009|url-status=dead|archive-url=https://web.archive.org/web/20090627023938/http://dkamhi.com/ssef%20type%20IIa.htm|archive-date=June 27, 2009}}</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| vauthors = Welbourn C |title=Identification of Synthetic Diamonds: Present Status and Future Developments, Proceedings of the 4th International Gemological Symposium|journal=Gems and 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.

Screening devices based on diamond type detection can be used to make a distinction between diamonds that are certainly natural and diamonds that are potentially synthetic. Those potentially synthetic diamonds require more investigation in a specialized lab. Examples of commercial screening devices are D-Screen (WTOCD / HRD Antwerp), Alpha Diamond Analyzer (Bruker / HRD Antwerp), and D-Secure (DRC Techno).