New Mineral Named After GIA’s John Koivula
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 Post subject: Gray diamond - fluorescence- question
PostPosted: Sun Feb 04, 2018 10:15 am 
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Need some help with this gray diamond - bought on ebay years ago for small money as natural untreated.
It is 0,29 ct with a nice deep pewter color.

It has a strong chalky blue fluorescence and a very short chalky yellow phosphorescence.

The LW fluorescence is uneven as you can see in the pics.

My question - could this be a sign for a treated stone? Or typical in natural untreated.

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 Post subject: Re: Gray diamond - fluorescence- question
PostPosted: Sun Feb 04, 2018 10:17 am 
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The LW UV pics...

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 Post subject: Re: Gray diamond - fluorescence- question
PostPosted: Mon Feb 05, 2018 1:40 pm 
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What do you think is the cause of the gray color? Minute inclusions (as is the situation with natural blacks) or perhaps a type IIb?


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 Post subject: Re: Gray diamond - fluorescence- question
PostPosted: Mon Feb 05, 2018 3:34 pm 
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Minute inclusions - a Tyndall effect with strong light from the side.

Seems that the fluorescence is weaker in the areas with a stronger effect... :-k

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