Editing Emerald (section)

== Synthetic emerald ==
[[File:Emerald.png|thumb|upright=0.45|left|Emerald showing its hexagonal structure]]

Both hydrothermal and [[flux method|''flux-growth'']] synthetics have been produced, and a method has been developed for producing an emerald overgrowth on colorless [[beryl]]. The first commercially successful emerald synthesis process was that of [[Carroll Chatham]], likely involving a lithium vanadate flux process, as Chatham's emeralds do not have any water and contain traces of vanadate, molybdenum and vanadium.<ref>{{cite book|last1=O'Donoghue|first1=Michael|title=Gemstones|date=1988|publisher=Springer Netherlands|location=Dordrecht|isbn=9789400911918|page=310|url=https://books.google.com/books?id=5BsyBwAAQBAJ&q=chatham%20emerald%20process%20vanadium&pg=PA310|url-status=live|archive-url=https://web.archive.org/web/20170330180757/https://books.google.com.au/books?id=5BsyBwAAQBAJ&lpg=PA310&dq=chatham%20emerald%20process%20vanadium&pg=PA310#v=onepage&q=chatham%20emerald%20process%20vanadium&f=false|archive-date=30 March 2017}}</ref> The other large producer of flux emeralds was [[Pierre Gilson]] Sr., whose products have been on the market since 1964. Gilson's emeralds are usually grown on natural colorless beryl seeds, which are coated on both sides. Growth occurs at the rate of 1&nbsp;mm per month, a typical seven-month growth run produces emerald crystals 7&nbsp;mm thick.<ref>Nassau, K. (1980) ''Gems Made By Man,'' Gemological Institute of America, {{ISBN|0-87311-016-1}}.</ref>

[[Hydrothermal synthesis|Hydrothermal]] synthetic emeralds have been attributed to [[IG Farben]], Nacken, [[Tairus]], and others, but the first satisfactory commercial product was that of [[Johann Lechleitner]] of [[Innsbruck]], Austria, which appeared on the market in the 1960s. These stones were initially sold under the names "Emerita" and "Symeralds", and they were grown as a thin layer of emerald on top of natural colorless beryl stones.  Later, from 1965 to 1970, the [[The Linde Group|Linde]] Division of [[Union Carbide]] produced completely synthetic emeralds by hydrothermal synthesis. According to their patents (attributable to [[Edith Flanigen|E.M. Flanigen]]),<ref>Geological Magazine "Hydrothermal process for growing crystals having the structure of beryl in an alkaline halide medium" {{US patent|3567642}} Issue date: 2 March 1971</ref> acidic conditions are essential to prevent the chromium (which is used as the colorant) from precipitating. Also, it is important that the silicon-containing nutrient be kept away from the other ingredients to prevent nucleation and confine growth to the seed crystals. Growth occurs by a diffusion-reaction process, assisted by convection. The largest producer of hydrothermal emeralds today is Tairus, which has succeeded in synthesizing emeralds with chemical composition similar to emeralds in alkaline deposits in Colombia, and whose products are thus known as “Colombian created emeralds” or “Tairus created emeralds”.<ref>{{cite journal|author1=Schmetzer, Karl |author2=Schwartz, Dietmar |author3=Bernhardt, Heinz-Jurgen |author4=Tobias Hager |url=http://www.gem-a.com/media/27904/2006%2030%201%20to%202.pdf |title=A new type of Tairus hydrothermally-grown synthetic emerald, colored by vanadium and copper |journal=Journal of Gemmology of Gemmological Association of Great Britain |volume=30 |issue=1–2 |year=2006–2007 |pages=59–74 |url-status=dead |archive-url=https://web.archive.org/web/20110711082633/http://www.gem-a.com/media/27904/2006%2030%201%20to%202.pdf |archive-date=11 July 2011  }}</ref> Luminescence in [[ultraviolet light]] is considered a supplementary test when making a natural versus synthetic determination, as many, but not all, natural emeralds are inert to ultraviolet light. Many synthetics are also UV inert.<ref>Hurlbut, Cornelius S. Jr. and Kammerling, Robert C. (1991) ''Gemology'', John Wiley & Sons, New York, p. 81, {{ISBN|0-471-52667-3}}.</ref>
[[File:SyntEmerald 0302.jpg|thumb|Emerald made by hydrothermal synthesis]]
Synthetic emeralds are often referred to as "created", as their chemical and gemological composition is the same as their natural counterparts. The U.S. [[Federal Trade Commission]] (FTC) has very strict regulations as to what can and what cannot be called a "synthetic" stone. The FTC says: "§&nbsp;23.23(c) It is unfair or deceptive to use the word "laboratory-grown", "laboratory-created", "[manufacturer name]-created", or "synthetic" with the name of any natural stone to describe any industry product unless such industry product has essentially the same optical, physical, and chemical properties as the stone named."<ref name=ftc>{{cite web |url=http://www.ftc.gov/bcp/guides/jewel-gd.htm |title=Guides for the Jewelry, Precious Metals, and Pewter Industries |publisher=U.S. [[Federal Trade Commission]] |date=30 May 1996 |access-date=30 July 2010 |url-status=live |archive-url=https://web.archive.org/web/20080907034021/http://www.ftc.gov/bcp/guides/jewel-gd.htm |archive-date=7 September 2008  }}</ref>