Post subject: Re: Yellow Sapphire With Report From GTLI
Posted: Sun Jan 25, 2015 6:45 am
Valued Contributor
Joined: Wed Oct 22, 2008 5:00 am Posts: 344 Location: Finland
Actually, they have FTR & XT! and the stone is corrundum.... something we mortals will never afford or even understand
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.
Post subject: Re: Yellow Sapphire With Report From GTLI
Posted: Sun Jan 25, 2015 4:34 pm
Established Member
Joined: Wed Sep 10, 2014 10:54 pm Posts: 43
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
Post subject: Re: Yellow Sapphire With Report From GTLI
Posted: Tue Jan 27, 2015 1:16 am
Gold Member
Joined: Mon May 14, 2007 11:00 am Posts: 1133 Location: Monterey, CA
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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