JOGS International Gem Show April 7-18 Tucson Expo Center
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 Post subject: Re: Emerald?
PostPosted: Wed Apr 25, 2012 1:45 pm 
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Hello all,

I appreciate the comments and I want to respond and explain in more detail however I have to leave now for the airport, so it may take a day. In general I think it is probably easiest to shortly explain that there are more traditional/historic approaches that refer to color only however an increasing trend, particular in Europe where I spent a considerable amount of my gemological career, there are efforts to try and complement the color description with additional criterion that is a little more objective or quantifiable.

More on this later.

Best regards,
Chris Smith


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 Post subject: Re: Emerald?
PostPosted: Wed Apr 25, 2012 2:59 pm 
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Have a great trip Christopher! I look forward to your post on this topic when you find the time.

I'd also appreciate your inclusion of comments relating to determining an alexandrite I.D. in this thread or a separate one. Some gemologists make a distinction between "color-changing chrysoberyl" and "alexandrite chrysoberyl."

They say any chrysoberyl showing color change other than reddish to greenish can't be called alexandrite. Some also insist that a chromium spectrum be detectable, along with red fluorescence. The strength of the red/green change is also considered determinative (though that seems a bit subjective to me).

Most of the non-red/green chrysoberyls I've seen come from Africa. I also have a number of Indian stones (Andhra Pradesh) that have wonderful strong daylight blue-green color and turn varying degrees of grayish-pink or grayish-purple in incandescent. They all fluoresce strongly to moderately red but I can't detect chromium lines with my OPL (although someone more skilled might!) What do I call them? Is the chromium spectrum absolutely determinative?

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 Post subject: Re: Emerald?
PostPosted: Thu Apr 26, 2012 6:03 am 
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I have seen that stone, and it is greener. Greener still are some I found. The color compares to the Crabtree emeralds I found in quartz. I will see if I can get time to get a picture today.

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 Post subject: Re: Emerald?
PostPosted: Thu May 03, 2012 1:37 pm 
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Hi to everybody!
Ok I studied gemology in the German Gemological Association in Idar-Oberstein and, for what I have always known, they say "no chrome, no emerald", i.e. if you don't see the double line on red in spectroscope, it is just a green beryl (or a red corundum, etc.). Moreover: there are bryls which are half-green and half-blue, I found some in Habachtal in Austria!
Greetings from Italy by Riccardo.


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 Post subject: Re: Emerald?
PostPosted: Fri May 04, 2012 5:50 pm 
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Welcome fellow digger :-)!

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 Post subject: Re: Emerald?
PostPosted: Fri May 04, 2012 7:55 pm 
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Riccardo Modanesi wrote:
Hi to everybody!
Ok I studied gemology in the German Gemological Association in Idar-Oberstein and, for what I have always known, they say "no chrome, no emerald", i.e. if you don't see the double line on red in spectroscope, it is just a green beryl (or a red corundum, etc.). Moreover: there are bryls which are half-green and half-blue, I found some in Habachtal in Austria!
Greetings from Italy by Riccardo.


So using that method then you would rule out all the Brazilian and African ones that get their green due to Vanadium?

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 Post subject: Re: Emerald?
PostPosted: Mon May 07, 2012 10:58 am 
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Hi Barrett and hi to everybody!
Oh no, not me! Using that method, the Germans call those (wonderful!!!) green beryls "Vanadium-beryls", and not emeralds! And the same way they call "pink sapphires" or "red sapphires" :o :shock: all of the corundums taking their colour not to chrome, i.e. they don't call them rubies! :!:
Greetings fom Italy by Riccardo. :smt002


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So using that method then you would rule out all the Brazilian and African ones that get their green due to Vanadium?


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