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 Post subject: Copper bearing tourmalines
PostPosted: Sat Oct 21, 2006 3:38 am 
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Are all copper bearing tourmalines considered to be "Paraiba Tourmaline" in the trade. I saw a certificate issued by the Gem and Jewelry Institue of Thailand for a yellowish green tourmaline. It states the stone is natural and Copper trace element can be detected. However, in another certificate issued by the same lab on a blue toumaline, it states based on the presence of Copper trace element, the gem can be considered as "Paraiba Tourmaline" in the gem market. Both of the stones are supposed to be from Mozambique.

It seems there is a difference in standard to consider whether a copper bearing tourmaline is "Paraiba". Is it based on the amount of Copper detected, or the hue of the gem or ??? :?: I am hoping that some one can claify that.

Thanks
Rebecca


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 Post subject: Re: Copper bearing tourmalines
PostPosted: Sat Oct 21, 2006 12:21 pm 
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Rebecca wrote:
It seems there is a difference in standard to consider whether a copper bearing tourmaline is "Paraiba". Is it based on the amount of Copper detected, or the hue of the gem or ??? :?: I am hoping that some one can claify that.

LOL, a LOT of us hope for the same thing! I'm not part of the colored stone industry's arcane and elite power structure. But I've read recently that the American Gem Trade Association Gemological Testing Center (AGTA GTC) is reconsidering use of the term "Paraiba" on lab certs.

Last May AGTA GTC announced it would call all copper-bearing tourmaline "paraiba" no matter what the origin. But in June AGTA members announced their unhappiness with that decision and the matter is currently being reviewed by AGTA GTC's board of governors.

My question is how does whatever AGTA GTC decides affect what other labs here and around the world do? Are we to believe an AGTA decision is binding on GIA and other certifying agencies around the globe? I think not but maybe I'm wrong. Certainly I've observed a degree of noblesse oblige between labs but when it comes down to hard dollars, dinars, yen or euros I wonder how much one lab's opinion counts in the great scheme of things?

Rick Martin


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 Post subject:
PostPosted: Sat Oct 21, 2006 12:42 pm 
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http://gemologyonline.com/Forum/phpBB2/ ... ht=paraiba and http://www.palagems.com/paraiba.htm


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 Post subject:
PostPosted: Sat Oct 21, 2006 3:42 pm 
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hmm... perhaps next we will see people trying to sell "copper-bearing schorl" for thousands a carat!


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 Post subject:
PostPosted: Sat Oct 21, 2006 5:08 pm 
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Doos wrote:
http://gemologyonline.com/Forum/phpBB2/viewtopic.php?t=602&highlight=paraiba and http://www.palagems.com/paraiba.htm


Thanks for the links. I read them all but I am still confused what is considered to be Paraibas:

1) Color: Are the true Paraibas always greenish blue in color? I know the cuprian tourmalines come in a variety of colors so should they be called Copper bearing green/violet/blue tourmalines? In the GIA colored stone class materials, it is stated that "Paraiba tourmalines appear in a range of greenish blue, bluish green, green, blue and violet hues" so it seems Paraibas has a lot of colors including green. They are heat treated to improve the colors but does that mean the untreated ones are not Paraibas since the color may be a little off?

2) Origin: I am totally lost in this. While the Nigerian goods are not in the league, some of the Mozambique come very close to the Brazilian. If they look similar, one would assume that they should be priced simialr too.


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 Post subject:
PostPosted: Sat Oct 21, 2006 5:27 pm 
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Hi Rebecca,

1) Paraiba is a location in Brazil where the untreated copper rich tourmalines are found. Some copper rich tourmalines are found around the west coast of Africa and they may be heat treated to give the same appearance. (dunno if the Brazilian cousins may be heat treated aswell, but I suspect some of them are).
In short it is the location that determines "paraiba" or not .. but that is under very heavy debate.
What they all have in common is the "neon glow" no matter what color.

2) As stated above (and the links) .. origin and the name giving is under heavy debate.
Remember that once Brazil and Nigeria were joined at the hip.


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 Post subject:
PostPosted: Sat Oct 21, 2006 5:40 pm 
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I have several posts in my blog: GemWise on this subject: Take a look! You can access from the main page.

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Author: The French Blue: http://www.thefrenchblue.com and Secrets Of The Gem Trade: http://www.secretsofthegemtrade.com


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 Post subject:
PostPosted: Sun Dec 31, 2006 1:13 am 
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What of the claim by the Brazilians that the finest Paraiba is both copper and gold bearing. AGTA doesn't test for gold but I have heard this more than once from dealers. Anyone know anything?
I have to ask around.


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 Post subject:
PostPosted: Sun Dec 31, 2006 11:20 am 
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We actually had a thread on that ages ago started by Ux4.
I'll have to see if I can find the specifics on it.


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 Post subject:
PostPosted: Sun Dec 31, 2006 1:11 pm 
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If you want to see something funny, do a google search for "gold content in paraiba tourmaline'
I think every dealer got a mimeographed copy of the claim. Identical word for word. :wink:

Maybe you can contact the German lab that supposedly made this discovery. http://www.dsef.de/html/about_us.html

Pb is the only metal I've seen mentioned that MAY lend some origin identification information.

On another note, Paraiba International that claims to sell only Brazilian Paraiba claims that all of this material should be assumed to be heated.


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