Joined: Sat Jun 07, 2008 4:38 pm Posts: 125 Location: victoria, bc, canada
Hi,
The use of the adjective "cuprian" seems to be accepted within the trade for green/blue tourmaline that isn't saturated enough to be called paraiba-like.
But, in the absence of lab certification, what is the basis for describing it as cuprian?
A paraíba tourmaline is a blue (electric blue, neon blue, violet blue), bluish green to greenish blue or green elbaite tourmaline, of medium to high saturation and tone (relative to this variety of tourmaline), mainly due to the presence of copper (Cu) and manganese (Mn) of whatever geographical origin.
some labs also classify not Brazilian paraíba by Paraiba-type designation
Joined: Sat Jun 07, 2008 4:38 pm Posts: 125 Location: victoria, bc, canada
Hi again,
In my original post I said:
"But, in the absence of lab certification, what is the basis for describing it as cuprian?"
I should have said, ...in the absence of lab certification proving that copper is present, what is the basis for describing it as cuprian?
My understanding is that testing (to determine the presence of copper as the color-causing agent) is expensive and requires equipment that most labs don't have--if this is true, I suspect few of the "cuprian" tourmalines have been tested but many people use the term anyway.
So, it seems that terminology means whatever the speaker wants it to mean?
Joined: Fri Feb 24, 2006 1:20 am Posts: 2756 Location: Southern California, U.S.A.
billkent wrote:
So, it seems that terminology means whatever the speaker wants it to mean?
Bill, this is nothing new. To quote Humpty-Dumpty's chat with Alice:
“When I use a word,” Humpty Dumpty said, in rather a scornful tone, “it means just what I choose it to mean—neither more nor less.” “The question is,” said Alice, “whether you can make words mean so many different things.” “The question is,” said Humpty Dumpty, “which is to be master that’s all.”
One encounters many variations of Humpty-Dumpty in the gem trade.
Joined: Tue Jun 03, 2008 4:40 pm Posts: 2667 Location: South Dakota
All tourmalines that derive their color from copper can be called cuprians.... but not all cuprians can be called paraiba..... but all paraiba's can be called cuprian hmmmmm
_________________ MrAmethystguy ~ Some jokes just fluorite over my head!
Joined: Wed Oct 22, 2008 5:00 am Posts: 344 Location: Finland
VIS-NIR spectrum has been demonstrated as reliable tool for detecting copper in tourmaline. While it doesn't produce quantitive analysis it's significantly cheaper than any of the more sophisticated methods.
Joined: Sat Jun 07, 2008 4:38 pm Posts: 125 Location: victoria, bc, canada
How many of us, besides myself, have used a phrase such as "paraiba-type" in an appraisal, without having lab certification of the presence of copper/manganese?
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