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How rare is it for Amethysts to have 3 way pleochroism?

0 votes

this is a ceylonese amethyst not heated or treated in anyway other than native cut and set. photo taken inside in natural daylight at midday in the southern hemisphere.

asked Jul 27, 2016 by Blacksorrento (120 points)
edited Jul 27, 2016 by Blacksorrento

1 Answer

0 votes
Amethyst should not be pleochromic - it is a monochromatic gemstone. If it is indeed exhibiting strong pleochroism perhaps your gemstone is iolite, not amethyst.
answered Sep 18, 2016 by hershel (49,730 points)
Thank you for your answer hershel.
As far as I know it has been assayed definitely as an Amethyst. The stone was evaluated and its RI and SG fell within Amethysts parameters. Having said that though, I am only going on what the certified gemologist told me. They said it showed a strong pleochroism of blue, violet and red.  I have tried to research this and found out that Amethysts are as you said non pleochromic, hence the reason I asked the question in the first place.  3 people in the fine jewellery trade have told me it is a most unusual stone. As a lay person, how does one simply test for pleochromic tendancies? I have photographed this stone on many occasions, it is a chameleon. it can display itself being indigo blue, raspberry red, magenta and violet depending on what natural daylight it is in. I have even seen it totally pink but have not been able to capture that on camera.
Maybe your Stone is AMETHYSTINE, which displays all the colors that you have mentioned. Some amazing pieces coming out of Georgia, USA, Exact location?? and Im sure that there are others around the World, Like Ceylon for example. Also i have seen in my research that Amethyst is pleochroic (en.wikipedia.org/wiki/Pleochroism) as is Citrine(Confirmed on other sites), so probably Ametrine as well.  I know Wikipedia is not a great source for the Truth, but it is mentioned and here you see an example so 1+1 =2
A Second Source and Confirmation that Amethyst can be Pleochroic, may be found at, https://nature.berkeley.edu/classes/eps2/wisc/pleo.html. This is a much more credible and reputable source than Wikipedia.
Thank you for those references, your second one from Berkeley gives credence to what I see with my own eyes. So thank you for posting.
I read up about amethystine, I don’t think that applies to my stones, although I took onboard what you said.
I actually have two stones that do this, one is a pendant pictured and another is in a ring. They both display the same pleochroism, the pendant shows more vivid.
Any person in the gem trade who sees them, tell me they are really something special, and never to let go of them. One jeweller even said he had heard about amethysts like these, but never thought to see one in his lifetime. When you take the stone out of its setting and rotate it through a jewellers light, it changes through a myriad of colour before your eyes, I was mesmerised just watching it happen, truly jaw dropping.  Didn’t have the presence of mind to take a video of it, did I.....!!!!!
There are always exceptions to the rule that is what makes gemology so interesting.
Recently I met a lady who came from Sri Lanka, she wore an amethyst ring, I showed her photos of mine, and she told me that amethysts like that have a special name(which eluded her) and are very highly prized.
As far as I know, it is a Ceylonese amethyst. They were bought in Ceylon in 1964 as part of a set.
 


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