New Mineral Named After GIA’s John Koivula
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 Post subject: phosphorescence of diamonds
PostPosted: Tue Jul 17, 2012 4:50 am 
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Hello,

my first posting....

I have a question about phosphorescent diamonds:
we got some yellow and brownish faceted diamonds for appraisal- three of them with interesting luminescence:
2 yellow and 1 brownish diamond have a (very light greenish) yellow fluorescence (LWUV stronger than SWUV) and one of them (yellow) a long lasting phosphorescence, nearly 60 sec. We are using a 15W lamp in a darkened room.

Additional informations:
I couldn't find any cape lines in the VIS - so these are no Type Ia; the long lasting phosphorescent stone has many inclusions, such as irregular growth structures in small lines (see pictures - same stone but different lightning); in methyleniodid the stone shows very strong anomalous birefringence in bright colours (that would indicate natural diamond...?!); Diamond Spotter shows no transparency;

Are there any natural diamonds (exceptional IIb diamonds) with such phosphorescence?
Unfortunately I couldn't find more informations about phosphorescence of diamonds...

Thanks,

Adeline


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 Post subject: Re: phosphorescence of diamonds
PostPosted: Tue Jul 17, 2012 1:39 pm 
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Location: San Francisco
This article might be useful:
The “Type” Classification System of Diamonds and its Importance in Gemology
[pdfview]http://www.shoregold.com/_resources/The-Type-Classification-System-of-Diamonds_C_Breeding_J_Shigley.pdf[/pdfview]


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 Post subject: Re: phosphorescence of diamonds
PostPosted: Tue Jul 17, 2012 2:25 pm 
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Thank you for the link but I read this article already...
I think that this stone must be a natural Type Ib diamond- but I never heard about such a phosphorescence in natural stones before that's why I am posting in this forum.


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 Post subject: Re: phosphorescence of diamonds
PostPosted: Tue Jul 17, 2012 5:28 pm 
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I've only heard of phosphorescence in Type II diamonds.
Lang Antiques owns the type IIB that Gems & Gemology did the article on last year regarding extreme phosphorescence in type II diamonds. :D .


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