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Natural Science Forum / Earth Science / Mineralogy / June 2004detecting artificial color enhancements in amethyst and citrine
Is there any reliable method of conclusively determining whether amethyst has been color enhanced with radiation and/or heat? I have heard conflicting opinions on this issue from different "experts". I am now always suspicious of deep amethyst at any reasonable price. The same essential question applies to citrine and ametrine. Also, what percentage of ametrine has been artificially color enhanced? I have been told by some professionals that it is impossible to manufacture ametrine from amethyst; others have told me that any affordable ametrine is enhanced. I have always guessed that the latter is closer to the truth. This issue is important to me because most of my clients desire only "natural" stones. When I purchase stones, I must wholly depend on the word of my sources (who are, in turn, dependent on the word of their sources). The situation seems ideal for widespread deception. Can anyone provide a definitive answer (preferably supported by confirmable documented facts)? Oakenbone I was under the impression that heat treating amethyst produces either citrine or green quartz depending on specific materials and treatment. I do not think there is a method yet that darkens the color of amethyst. Synthetic quartz can be doped to produce both amethyst and citrine. You might check with the G.I.A. (Gemological Institute of America) to see what is the current status of gemstone treatments. Will E. > Is there any reliable method of conclusively determining whether > amethyst has been color enhanced with radiation and/or heat? I have [quoted text clipped - 15 lines] > > Oakenbone Here is an article I found on the GIA site reporting that "huge amounts" of synthetic amethyst and ametrine are being produced and dumped on the market. From Gems & Gemology: Synthetic and Enhanced Gems from Russia At the recent International Gemmological Congress in Madrid, Spain, an update on synthetics, simulants, and gem treatments from Russia was provided by Dr. Vladimir S. Balitsky of the Institute of Experimental Mineralogy, Russian Academy of Sciences in Chernogolovka. Dr. Balitsky reports that several government institutes and about 30 companies have succeeded in manufacturing almost all known gems, whether their natural counterparts are abundant (such as some varieties of synthetic quartz) or uncommon (such as synthetic alexandrite, morganite, and moissanite), and representing a broad value range. In some cases, they are being manufactured in huge amountssuch as a few thousand kilograms annually of synthetic amethyst, ametrine, ruby, and sapphires of various colorsby every major method of synthesis (including hydrothermal, flux, Czochralski, and floating zone). Also being manufactured are large quantities of simulants, such as YAG, GGG, and CZ. The Russians are also enhancing the appearance and/or physical characteristics of several natural gems. These include agate, amazonite, amber, charoite, corundum, danburite, heliodor, lazurite, nephrite, demantoid garnet, quartz, topaz, and turquoise. A variety of techniques are used, such as heat treatment, impregnation, and dyeing. Gem treaters are developing new surface-coloring technologies as well. For example, they are now using a high-temperature process that chemically alters the surface of stones to turn colorless and pale-colored sapphires an attractive blue or orange, and topaz an orangy yellow (see figure: 1.17 ct reddish orange sapphire and 2.62 ct orangy yellow topaz). Quartz is also color enhanced by this process. The future will likely see increased production of larger and better synthetic diamonds and other gems, as well as advances in enhancement techniques. Clearly, Russia is a leader in these fields. > I was under the impression that heat treating amethyst produces either > citrine or green quartz depending on specific materials and treatment. I do [quoted text clipped - 22 lines] > > > > Oakenbone The thing I have wondered, if I can't tell the difference, what's the difference? Why should I care?  Signature- Charles - -does not play well with others Appraisals, insurance, IRS red flags, paying full price for mass produced goods, personal taste, Etc. Will E. > The thing I have wondered, if I can't tell the difference, what's the > difference? Why should I care? > The thing I have wondered, if I can't tell the difference, what's the > difference? Why should I care? The value of the stone as an investment. Not all people buy gems to wear, some buy them as others buy gold, because of their intrinsic value. If you are just wanting a pretty blue rock to put on your finger, it really doesn't matter. But if you put out thousands of dollars for a diamond, and found out later it was cubic zirconia, you would have been cheated, would you not? And that would make you angry. Many stones come with certifying papers these days. Now, of course, those papers can be faked even easier than the stones can be enhanced, however there are criminal penalties for faking the certification, whereas it is perfectly legal to enhance stones, only not legal to pass them off as untreated and natural. The only way to really be sure of the authenticity and naturalness of a stone is to be able to track the stone from mine to your purchase. This is sometimes possible with lapidarists, and small shops; rarely is it possible for large shops (except the most elite, and even they get duped occasionally.) But let the buyer beware. If the deal is 'too good to be true' it usually isn't. |
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