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 Post subject: Most likely ID for gem that changes colour.
PostPosted: Wed May 05, 2021 8:21 am 
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Hi everyone, and thanks in advance for your knowledge. I sell gold and silver jewellery in Australia and recently came upon a 14k Russian gold ring that had what I thought was an amethyst... only when I examined it under my loupe that has a florescent light, it turned a green/blue colour. I've realised now that the purple shade changes too, depending on the lighting. Under more yellow lighting it is a richer, darker shade of purple, and under whiter lighting it is a much paler purple. So far I've only noticed it go green when I have the abovementioned loupe light directly on it, but will experiment more tomorrow (it's night here in Australia). It's never happened with other stones I have, so definitely isn't the loupe light doing weird things.

From what I've googled alexandrite usually changes in the other direction - green to purple. The stone also appears to be quite soft, as I can see wear to the facets under the 15x loupe. I believe it to be a natural gemstone (not glass or synthetic).

Any ideas? Fluorite? Colour changing garnet? Open to help and advice, Thanks.


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 Post subject: Re: Most likely ID for gem that changes colour.
PostPosted: Thu May 06, 2021 5:43 pm 
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Picture would help.


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 Post subject: Re: Most likely ID for gem that changes colour.
PostPosted: Fri May 07, 2021 4:32 am 
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It reminds me of this thread :
viewtopic.php?f=27&t=26012

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 Post subject: Re: Most likely ID for gem that changes colour.
PostPosted: Fri May 07, 2021 12:51 pm 
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Yes and in that thread I called it Amethyst, but here we start at a maybe Fluorite.
MillyMolly why do you believe it is a natural? Prong abrasion to a gemstone would not automatically make it a softer gem material. We have a lot gems of harder classes of gems show abrasion mostly due to loose setting, and possibly the stone already had the abrasion and was reset. The list goes on as to why.
I agree with Barbra, need a picture and without an image it is like that phone call we get everyday where all there is a vague interpretation of values and Google searching to go by.
For a true I'd take it to a qualified individual for proper testing. Like Barbra.

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 Post subject: Re: Most likely ID for gem that changes colour.
PostPosted: Sat May 08, 2021 3:01 am 
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When you say "most likely ID for gem that changes color" the answer is almost always vanadium doped synthetic sapphire.
Far from the only option, but by far the most probable. Large color changing stones are expensive (with the possible exception of fluorite which is more moderately priced) so they don't tend to be separated from their provenance so easily (and color change fluorite is enough of a collector's stone that it is also unlikely to end up mixed with other things, and soft enough to be unlikely to survive if it did). In comparison there are tons and tons of synthetic cc sapphires which were sold decades ago, often mislabeled as alexandrite, and they pop up everywhere.

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