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<p>[QUOTE=&quot;Ce BCA, post: 3839356, member: 18716&quot;]Since readily available synthetic amethyst nose dived the market in the 80&#039;s it&#039;s been very hard to tell the difference between the synthetic and the natural forms.&nbsp; Some estimates suggest over 90% of what comes to market now is synthetic. Both are often free of any telltale inclusions, but I came across this posted on a jewellery forum.</p><p><br /></p><p><a href="https://www.gia.edu/doc/A-Simple-Procedure-to-Separate-Natural-from-Synthetic-Amethyst-on-the-Basis-of-Twinning.pdf" target="_blank" class="externalLink ProxyLink" data-proxy-href="https://www.gia.edu/doc/A-Simple-Procedure-to-Separate-Natural-from-Synthetic-Amethyst-on-the-Basis-of-Twinning.pdf" rel="nofollow">https://www.gia.edu/doc/A-Simple-Procedure-to-Separate-Natural-from-Synthetic-Amethyst-on-the-Basis-of-Twinning.pdf</a></p><p><br /></p><p>I&#039;m not sure &#039;Simple&#039; is the best description for people at home (for a lab maybe more so), but it is possible.&nbsp; I don&#039;t have any unmounted well cut amethysts to test so I had to use mounted stones, the bigger the stone, the easier it is.&nbsp; I couldn&#039;t get it to work with a polariscope, possibly as the mounting was a big hindrance, also I couldn&#039;t get enough visual acuity on it.</p><p><br /></p><p>So I bought two polarisers for my microscope, one for the objective the other to polarise the transmitted base light.&nbsp; It worked, cross polarised and angled through the right plane I can see the Brazil twinning in a natural stone, no immersion needed.&nbsp; It takes a bit of time to get the hang of, and I found a magnification of about 20x worked best (stones of 1-3 carat).&nbsp; I don&#039;t have any at the moment but it is supposed to work on ametrine too.&nbsp; This test doesn&#039;t determine if it has been heat treated though.</p><p><br /></p><p>All it cost was two cheap polarisers from ebay (£17 for a 55mm and a 95mm that I needed for my setup) and now I can ask a premium for natural stones over synthetics, so it will easily pay for itself in one sale.&nbsp; If you have a microscope as long as you can get the polarisers in place you should be able to do it as well.&nbsp; Certainly worth a try at the cost.[/QUOTE]</p><p><br /></p>

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