Post subject: Re: How to identify natural amethyst vs heated amethyst
Posted: Sat Mar 21, 2020 5:00 pm
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Joined: Thu May 12, 2016 2:18 am Posts: 1542
If you are talking about heating to lighten the color a little, then I don't think there is a definitive way to tell.
If you are talking about Amethyst that has been heated to Citrine then the key is the dichroscope.
The iron in Amethyst and natural Citrine acts in the typical manner of trace elements in the crystal lattice. It changes the absorption spectrum to create the color. Therefore the color is influence by the crystal orientation, and exhibits dichroism. It is obvious and easy to check.
In Amethyst that has been heated to Citrine, the iron has been oxidized by the heat treatment. In other words it has rusted into a yellow to brown color. Since this oxidized iron is now basically acting as a stain rather than integrated in the crystal structure, it doesn't show dichroism. It is stained equally in all crystal directions.
Post subject: Re: How to identify natural amethyst vs heated amethyst
Posted: Sun Mar 22, 2020 3:08 am
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Joined: Mon Sep 03, 2012 11:32 am Posts: 96
Thanks for the knowledge. I am asking about the light purple colored amethyst heated/radiated to intensify color into dark purple . Is it possible? If its the case then can we identify it?
Post subject: Re: How to identify natural amethyst vs heated amethyst
Posted: Sun Mar 22, 2020 12:05 pm
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Joined: Thu May 12, 2016 2:18 am Posts: 1542
No, you heat over dark Amethyst to lighten it, as far as I know there is no way to darken light Amethyst.
When you irradiate quartz it turns to brownish to blackish. This may give it a darker tone, but it also muddies the color and produces unattractive stones. When you heat the stones you can remove the irradiated color back to the original color.
I wouldn't worry about treatment on amethyst. Those treatments that are possible aren't really detectable, and the real enemy is the widespread undisclosed synthetic amethyst which have flooded the market.
Post subject: Re: How to identify natural amethyst vs heated amethyst
Posted: Sun Mar 22, 2020 3:17 pm
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Joined: Thu May 12, 2016 2:18 am Posts: 1542
Yes, the synthetic Amethyst is not easy for most to detect, and a huge amount of this is on the market being sold as natural. The big problem is that at the price Amethyst sells for it is most often not worth proving natural/synthetic in cut stones.
I buy my Amethyst (Ametrine, Citrines, Prasiolite) rough direct from the mine either in Rwanda/Zambia or Brazil/Uruguay/Bolivia so I know the origin and treatments applied. But once the stones are cut and on the market who really knows.
Post subject: Re: How to identify natural amethyst vs heated amethyst
Posted: Tue Mar 24, 2020 9:00 pm
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Joined: Mon Sep 03, 2012 11:32 am Posts: 96
I guess with amethyst, most people dont bother to check wether its real or synthetic as its not that expensive than other semi precious stones and also not easy to detect aswell.
Post subject: Re: How to identify natural amethyst vs heated amethyst
Posted: Tue Mar 24, 2020 9:16 pm
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Joined: Thu May 12, 2016 2:18 am Posts: 1542
14megapixel wrote:
I guess with amethyst, most people dont bother to check wether its real or synthetic as its not that expensive than other semi precious stones and also not easy to detect aswell.
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