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 Post subject: Nephrite, Atinolite or glass cat eye?
PostPosted: 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?
PostPosted: Sun Aug 22, 2021 11:26 am 
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Get them tested. I see no reason looking at the back of the stone that rules out Chrysoberyl.


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 Post subject: Re: Nephrite, Atinolite or glass cat eye?
PostPosted: Sun Aug 22, 2021 11:33 am 
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:) thank you 1bwana1


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 Post subject: Re: Nephrite, Atinolite or glass cat eye?
PostPosted: Sun Aug 22, 2021 11:42 am 
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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.

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 Post subject: Re: Nephrite, Atinolite or glass cat eye?
PostPosted: Sun Aug 22, 2021 11:56 am 
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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

Report back.


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 Post subject: Re: Nephrite, Atinolite or glass cat eye?
PostPosted: Sun Aug 22, 2021 12:29 pm 
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Thank you for everyone’s feedback! Checked for honeycomb on top and sides of both stones- no honeycomb or dots. :)


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 Post subject: Re: Nephrite, Atinolite or glass cat eye?
PostPosted: Sun Aug 22, 2021 12:38 pm 
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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.


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 Post subject: Re: Nephrite, Atinolite or glass cat eye?
PostPosted: Wed Nov 03, 2021 9:20 am 
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So it turns out the stones above are a 6ct and 19.6ct prehnite…. Does anyone have any information on this type of stone and what it’s value might be?


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 Post subject: Re: Nephrite, Atinolite or glass cat eye?
PostPosted: Wed Nov 03, 2021 12:03 pm 
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No, I don't believe either of them are prehnite.


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 Post subject: Re: Nephrite, Atinolite or glass cat eye?
PostPosted: Wed Nov 03, 2021 12:41 pm 
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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.

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Last edited by glhays on Wed Nov 03, 2021 12:47 pm, edited 2 times in total.

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 Post subject: Re: Nephrite, Atinolite or glass cat eye?
PostPosted: Wed Nov 03, 2021 12:44 pm 
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Prehnite and nephrite can be hard to separate (just by the numbers) with typical home lab tools because their properties overlap.

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 Post subject: Re: Nephrite, Atinolite or glass cat eye?
PostPosted: Wed Nov 03, 2021 3:07 pm 
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I took the stones to a gemologist with over 30 years of experience- could he be wrong?


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 Post subject: Re: Nephrite, Atinolite or glass cat eye?
PostPosted: Wed Nov 03, 2021 11:21 pm 
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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.


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 Post subject: Re: Nephrite, Atinolite or glass cat eye?
PostPosted: Thu Nov 04, 2021 12:47 am 
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Thank you Barbra, I am going to enquire from the gemologist.


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 Post subject: Re: Nephrite, Atinolite or glass cat eye?
PostPosted: Thu Nov 04, 2021 12:52 am 
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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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