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 Post subject: Cobalt-doped glass-filled sapphires
PostPosted: Fri May 24, 2013 8:07 am 
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The Australian Gemmologist has just published a comprehensive article on these treated gems from the team at the Gem and Jewelry Institute of Thailand. You can see it online at this link:

http://www.ruby-sapphire.com/glass-filled-sapphire.htm

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 Post subject: Re: Cobalt-doped glass-filled sapphires
PostPosted: Fri May 24, 2013 8:18 am 
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Great, Dick!
thank you very much for sharing that. =D>


ciao
albé

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 Post subject: Re: Cobalt-doped glass-filled sapphires
PostPosted: Fri May 24, 2013 3:58 pm 
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Hey Dick,

one line got me thinking...

Quote:
But more importantly, all of the stones tested showed a strong red to orange-red when viewed with the Chelsea filter. Both natural and synthetic blue sapphires show no red.


I've come across a synthetic sapphire (which I don't have here at the moment, of course :evil: ) that fluoresced red in high intensity halogen light. What could be the chromophore there?

Attachment:
Cobaltdopedsapphire.jpg
Cobaltdopedsapphire.jpg [ 179.34 KiB | Viewed 2316 times ]


I thought it was cobalt back then cause cobalt doped spinel does this too but I now have learned that cobalt isn't on John E's list of possible chromophores in sapphire... or is it?


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 Post subject: Re: Cobalt-doped glass-filled sapphires
PostPosted: Sat May 25, 2013 7:50 am 
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Great article with very good identifying techniques covered. It appears that Barbra's favorite gemological tool, the Chelsea filter, is one of the main tools to carry when shopping for Sapphire now. :mrgreen:
Ted Themellis contacted me several months ago about this treatment as he was doing some research on how fast it was spreading around. I reported that I have not found them yet at the Burmese border, however, it is only a matter of time.
Best regards, Lee

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 Post subject: Re: Cobalt-doped glass-filled sapphires
PostPosted: Sat May 25, 2013 3:08 pm 
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Tim wrote:

I've come across a synthetic sapphire (which I don't have here at the moment, of course :evil: ) that fluoresced red in high intensity halogen light. What could be the chromophore there?

Could it be a Tairus synthetic with chromium? http://www.gia.edu/doi/10_5741-GEMS_33_3_188

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 Post subject: Re: Cobalt-doped glass-filled sapphires
PostPosted: Mon May 27, 2013 4:33 pm 
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No idea, Rick, a bit of chromium would be a possibility. I briefly looked at it today, one of my students stuck it in a ring, no sign of a cobalt spectrum.

So a rectumfication on that other thread: that wasn't a cobalt doped sapphire... they don't exist. (deleted the remark in question in that thread).


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 Post subject: Re: Cobalt-doped glass-filled sapphires
PostPosted: Thu Jun 13, 2013 4:06 pm 
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Back on subject... ;)
Here is a shot of air bubbles in a cobalt-doped glass filled sapphire. You can also see the color is in patches and streaks where the glass filling is present. The stone is a cabochon of around three carats.
Image

Forgot to mention, the stone is very nicely red if looked upon through the Chelsea Filter.

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 Post subject: Re: Cobalt-doped glass-filled sapphires
PostPosted: Sat Jun 15, 2013 5:04 am 
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Have you tried doing that same shot with the filter in between the objective and the stone?


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 Post subject: Re: Cobalt-doped glass-filled sapphires
PostPosted: Sat Jun 22, 2013 4:38 am 
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Nope... ;) Not yet.

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