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 Post subject: Zircon vs. Tourmaline
PostPosted: Mon Mar 25, 2013 7:12 pm 
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Hello,

I have a gemstone mounted in a ring that was sold to me as a Tanzanian Zircon (unheated). It very much resembles a apricot-pink/brown tourmaline. How can I tell without dismounting the stone, if at all, what it is? I have already had it looked at and two out of three people seem to believe it is a tourmaline but I can't get anyone who has made a visual-only assessment (at various jewelry stores) to explain why it appears to be a Tourmaline aside from the color resemblance. To me it more resembles a so-called blush zircon but it also seems to color-shift under different light going from an orange-pink to purple-brown. I collect various color Zircon gemstones, hence the question.

I appreciate the assistance!


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 Post subject: Re: Zircon vs. Tourmaline
PostPosted: Mon Mar 25, 2013 8:58 pm 
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Hello and welcome!
With access to gemological instruments the separation would be easy.
Will the mounting allow you to take a refractive index?
The refractive index for tourmaline is approximately 1.620-1.640, with a typical birefringence of 0.020
The RI for zircon is over the limit of the instrument.

A hand held spectroscope would also separate the two.
Zircon has a diagnostic absorption line at 653.5 nm.

Zircon has an exceptionally high birefringence, so with a loupe you should be able to see profound doubling of the back facets or internal characteristics.
Here's a pic I took of zircon some time ago:
Image

Hope this helps.


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 Post subject: Re: Zircon vs. Tourmaline
PostPosted: Mon Mar 25, 2013 9:33 pm 
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Thank you. It is a six-prong setting. The picture is very helpful for reference. I will see how much of an ID I can do given the setting.


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 Post subject: Re: Zircon vs. Tourmaline
PostPosted: Tue Mar 26, 2013 2:25 pm 
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GemView wrote:
Hello,
I collect various color Zircon gemstones, hence the question.

Learn the Hodgkinson Method and you can identify any zircon on sight. Google it.


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 Post subject: Re: Zircon vs. Tourmaline
PostPosted: Sat Mar 30, 2013 4:51 pm 
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I use a digital gem refractometer in instances like that.

_________________
http://adamasfacet.com


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 Post subject: Re: Zircon vs. Tourmaline
PostPosted: Sat Mar 30, 2013 6:35 pm 
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Correct me if I'm wrong, but I believe the digital units are reflectometers, not refractometers.


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