Post subject: Nephrite, Atinolite or glass cat eye?
Posted: Sun Aug 22, 2021 2:26 am
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Hello, I bought these to stones in a lot on auction. I have not been able to get them to a gemologist due to Covid. I have had some suggestions that they may be Actinolite cat’s eye. I have been told that they are not chrysoberyl because of the way the back of the stones look and are probably glass. I have checked under the loupe and there are no visible side dots pointing to fibre optic glass. Does anyone have any ideas?
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Post subject: Re: Nephrite, Atinolite or glass cat eye?
Posted: Sun Aug 22, 2021 11:42 am
Gold Member
Joined: Tue Apr 05, 2016 7:58 pm Posts: 1424 Location: San Marcos, CA
I was thinking the same, sure look like crysoberyl. Covid shouldn't be stopping you now, a few simple tests by a good gemologist will answer your questions very quickly.
Post subject: Re: Nephrite, Atinolite or glass cat eye?
Posted: Sun Aug 22, 2021 11:56 am
Site Admin
Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
View them, with magnification, perpendicular to top of the stone. Fiber optic glass will have a diagnostic honey-comb like profile. Review this thread: viewtopic.php?f=12&t=24249
Post subject: Re: Nephrite, Atinolite or glass cat eye?
Posted: Sun Aug 22, 2021 12:38 pm
Site Admin
Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
The effect is only visible from the sides, not the top. That being said, I think a few gemological tests are in order. I'd start with a spot RI and Specific Gravity.
Post subject: Re: Nephrite, Atinolite or glass cat eye?
Posted: Wed Nov 03, 2021 12:41 pm
Gold Member
Joined: Tue Apr 05, 2016 7:58 pm Posts: 1424 Location: San Marcos, CA
I have about 2kgs of tumbled prehnite and not one of them show chatoyancy. I am on the side with Barbra. How did you come to this conclusion? Prehnite. Value=$1.00p/gm, $1.50p/gm if it were chatoyant very unlikely Prehnite. I would stay with trying to id it as crysoberyl as it has a far better value and if it is not just old marbles cabbed.
Post subject: Re: Nephrite, Atinolite or glass cat eye?
Posted: Wed Nov 03, 2021 11:21 pm
Site Admin
Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
Yes. What was the identification based on? Refractive index? Specific gravity? Microscopic observation? Advanced spectrographic analysis? Or, a visual observation (aka a guess). I suspect the latter.
I'm going to bet that, for once, it actually wasn't visual observation, because there's no way to mistake one for the other outside of some very weird potential edge cases. I'd bet it's RI+ maybe SG (unlikely) and then looking in a table to see what's green, while disregarding nephrite/actinolite because they hadn't seen one as a cat's eye before. 30 years of experience doesn't necessarily help much for the more obscure stuff if you're spending your time in a typical jewelry store and not going out to shows, engaging with the community and reading the literature.
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