October 27-28—SACRAMENTO, CALIFORNIA: 82nd Annual Gem, Jewelry, Mineral and Rock Show; Sacramento Mineral Society; Sat. 10-5, Sun. 10-4
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 Post subject: Re: Yellow Sapphire With Report From GTLI
PostPosted: Sun Jan 25, 2015 6:11 am 
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roshanravan wrote:
FTIR & XTI???? does it mean XRD ????


or maybe XRF, we will never know...LOL

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 Post subject: Re: Yellow Sapphire With Report From GTLI
PostPosted: Sun Jan 25, 2015 6:45 am 
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Actually, they have FTR & XT! and the stone is corrundum.... something we mortals will never afford or even understand :D :D :D

Nice find Ross. About your question Raman would identify the material diagnostically, not just making distinction between corundum and topaz. Of course your RI test eliminates the corundum but additional tests would be required for being absolutely sure about topaz. In case of topaz photoluminescence would also tell if chromium has anything to do with the color.

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 Post subject: Re: Yellow Sapphire With Report From GTLI
PostPosted: Sun Jan 25, 2015 4:34 pm 
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mikko wrote:
About your question Raman would identify the material diagnostically, not just making distinction between corundum and topaz.


Thanks for clarifying. I was worried for a second, I though Bill Hanneman has implying that in some realm a Sapphire could infact give a reading that is similar to Topaz and that only Raman could dstnguish them. I was about to throw my gemology certificate in the bin #-o

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 Post subject: Re: Yellow Sapphire With Report From GTLI
PostPosted: Tue Jan 27, 2015 1:16 am 
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If one coats a sapphire with a material having the same RI as topaz, the refactometer will not "read" sapphire, as it is making a surface measurement. However, if one determines birefringence, one can tell that something is wrong.
A Raman makes BULK measurements.

Keep your gemology certificate, but learn the limits of your instruments.


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