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 Post subject: Detecting stabilized turquoise
PostPosted: Fri Jun 16, 2017 7:16 pm 
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Joined: Wed Jan 02, 2008 4:24 pm
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Location: East Tennessee
Hello Gemologists...
I wanted to test a large number of turquoise specimens for stabilization, but didn't have a hot needle. I used a small butane torch with a hot chisel tip on it. When laid on its side against flats on the turquoise, some of the specimens quickly popped and sweated as resin heated up and bubbled out of the stone and there waas an obvious plastic smell. Others did not do this, but did turn brown where the heated tip laid against the stone. My question is, is the browning (burning) characteristic of turquoise, or is it an indication of lower levels of resin (stabilization) being present?
TIA,
royjohn

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Faceting Custom Gems in East Tennessee
Buying and Selling Facet Rough
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 Post subject: Re: Detecting stabilized turquoise
PostPosted: Fri Jun 16, 2017 9:19 pm 
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Hi Royjohn.
The GIA has published some articles you may find helpful:

Impregnated and Dyed Turquoise

Polymer-Impregnated Turquoise

The Identification of Zachery-Treated Turquoise | Gems & Gemology


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 Post subject: Re: Detecting stabilized turquoise
PostPosted: Fri Jun 16, 2017 9:44 pm 
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Hello Barbra,
Thanks for the articles...from them I deduce that Zachary treated turquoise is hard to distinguish from natural by simple tests, but I didn't find an answer to my question as to whether a natural turquoise would turn brown when exposed to heat from a soldering iron.
Best,
royjohn

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Faceting Custom Gems in East Tennessee
Buying and Selling Facet Rough
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 Post subject: Re: Detecting stabilized turquoise
PostPosted: Fri Jun 16, 2017 9:49 pm 
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Might turn brown but it wouldn't bubble up and smell like plastic.

You know, you could just heat up a straight pin on the gas stove. Of course you have to be wearing your Ove' Glove when playing with fire.


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 Post subject: Re: Detecting stabilized turquoise
PostPosted: Fri Jun 16, 2017 10:31 pm 
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There was a pretty clear difference between those that bubbled, showed liquid on the surface and clearly smelled and those that took a while to turn brown in the spot where the chisel point contacted them, so I think I have my answer.
Thanks,
royjohn

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Buying and Selling Facet Rough
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