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 Post subject: Who says what Paraiba tourmaline is?
PostPosted: Fri Dec 09, 2016 12:37 pm 
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Now I have seen enough attempts at defining Paraiba tourmaline to confuse a better men than I am. And I don't really know the business well enough to judge who can be king of the hill, but my latest ride in the middle of early morn, on the inter net, really set me back.

I found myself, threw a convoluted path, on a GIA page labeled "Gemological Encyclopedia". I was on their Paraiba tourmaline page and I went for its definition. Well along with the rest of the standard fare, it stated that Paraiba tourmaline comes in a range of colors from violet to blue. WHAT HAPPENED TO GREEN? There was not a lot on the page and I noticed that there was a button to push to get more , so the adventure continued. On the second page of the GIA Encyclopedia, along with a bit more information was the statement that Paraiba tourmaline comes in a range of colors from green to blue. I HAD FOUND THE GREENS AND LOST THE PURPLES.

Now you should complain about me being picky, I am sure that it was just an oversight, BUT this internal inconsistency is ridiculous. And the colors that Paraiba tourmaline can come in is an area of misunderstanding and confusion. The Harmonization Committee appeared to excluded yellow greens and violets from the color range of Paraiba tourmaline, yet the dealers continue to included them in Paraiba or in some cases paraiba type tourmaline. So the trade is pushing the edges of the color range for Paraiba, the yellower greens are still great bright gems and violet/purple can be heated to Paraiba blues so what is the harm? (and they can be great bright gems also.)

So I drifted forward or backward in the electronic mist selected by Google and came to a site that I have seen many times. It carries only the highest quality and most expensive gemstones etc. and I never saw any tourmaline on it until Paraiba tourmaline graduate into the "precious" price range. In the middle of their older pages was a slice of history, the presentation of three paraiba like tourmalines, the master had just brought back from the East. They looked great and for an undisclosed price they could be mine. One was a fine purple, followed by a fine yellower green and the last one was RED.

Now the Batalia mine certainly produced gem quality red tourmaline and I have some reds from Mozambique that I feel confident have copper in them. But no serious article I have read included red as a Paraiba or paraiba like color. The reds and purples were great from Batalia, but that was not where the action was and they were basically destroyed by heating to make the blue greens we all love. So when the trade got around to attempt to formalize the definition of Paraiba, there weren't any reds and purples left to include in an already complex definition. You must remember that all the wonderful cuprian colors that have come out of Mozambique still look back to Brazil for the accept suite of colors that can be officially declared paraiba like. (Or more commonly just called paraiba with a bit of of African paraiba thrown in for spice.) To show how completely the market has rejected red/pink as even a cuprian color, The Gemstone Guide does not even list it as a cuprian color in its market driven tables of prices for any copper bearing tourmaline that did not come from Brazil.

If it wasn't for plain old money who would really care about which colors are which. I can say from personal experience that all quality cuprian tourmalines are beautiful to me. How much more I would pay for them, than a high quality indicolite from Namibia etc. is another question.

Bruce


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 Post subject: Re: Who says what Paraiba tourmaline is?
PostPosted: Sat Dec 10, 2016 12:29 am 
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I totally agree with you.
But, our opinions have minimal marketing (i.e. branding and buzz) sex appeal.


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 Post subject: Re: Who says what Paraiba tourmaline is?
PostPosted: Sat Dec 10, 2016 12:52 pm 
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Good day,

In the fourth edition of his book "Gems: their sources, descriptions and identification", revised by Anderson in 1983, Robert Webster wrote that he thought that tourmaline was one of the most interesting minerals from the scientific point of view. He added that it surpasses all other gems by its range of color. He cited the red, the pink, the violet, the brown, the colourless, the yellow, the green and the opaque black.

In the "Guide des pierres précieuses", 2008 of Schumann, all those colors are also cited.

I wonder why GIA has another point of view.

Best regards.

Brigitte


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 Post subject: Re: Who says what Paraiba tourmaline is?
PostPosted: Sat Dec 10, 2016 1:48 pm 
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Hello,

I forgot the blue. They cited the blue tourmaline.

Brigitte


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 Post subject: Re: Who says what Paraiba tourmaline is?
PostPosted: Sat Dec 10, 2016 2:30 pm 
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Thanks for the question.

I think the reason the industry has tried to limit the colors of Paraiba is historic. The original find in Brazil had many different colors, but the most uniquely beautiful/valluable was the cyan/windex/electric/neon blue to green colors. So heating was use to transform the natural colors that were found in Brazil to increase the tourmaline's value. When other discoveries were made in Africa that were similar enough to be included in the new variety Paraiba, the industry did not want to change the established, accepted range of colors that had come from Brazil, after most of the material had been heated. The range of blue to green was augmented by the more common unheated colors of blue to violet in Paraiba/paraiba type, in part because not all tourmaline, heavely included as it might be, is suitable to be heated.

So the color range ;limitations are only for the new variety Paraiba/paraiba like tourmaline and the older books would not cover the subject. (before 1989)

Bruce


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 Post subject: Re: Who says what Paraiba tourmaline is?
PostPosted: Sat Dec 10, 2016 4:53 pm 
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Hello Mister Bruce,

Thank you very much for your answer. I understand better now the situation. The Schumann's book is 2008 but it does not distinguish Paraiba tourmaline from other tourmalines. Schumann does cite Paraiba as a source for tourmaline.

If I understand well, copper is the element that makes the Paraiba tourmalines so special, besides their color. The confusion is that some tourmalines do not have the desired color for GIA but do have the copper element, which lack to the others tourmalines. And GIA give the name Paraiba base on the color and not scientifically fron the copper element?

Do I understand the situation right?

Best regards.

Brigitte


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 Post subject: Re: Who says what Paraiba tourmaline is?
PostPosted: Sat Dec 10, 2016 7:29 pm 
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You're getting closer. For the tourmaline to be the Paraiba variety it must have copper and a limited range of colors, green to blue and blue-purple to blue. (Tourmaline with copper normally comes in many more colors, but outside of the Paraiba/paraiba type color range they should be called cuprian. Some people feel that it should also come from state of Paraiba in Brazil. For tourmaline that has the same color ranges as Paraiba, but comes from outside Brazil, some people call it paraiba type/African paraiba. The tourmalines can appear identical with the only difference being their location of discovery.

There really is more to what is a Paraiba/paraiba type, than just color. The tourmaline should have a medium or higher tone level and have a neon glow-like brightness in my opinion. This is needed to give the tourmaline a bright nenon appearance, especially under lower levels of incandescent/yellowish light.

The point that got me going was internal inconsistancy in the "facts" the GIA was presenting about Paraiba/ paraiba type's color range.

Bruce


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 Post subject: Re: Who says what Paraiba tourmaline is?
PostPosted: Sat Dec 10, 2016 8:32 pm 
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I'm sure you are aware, Bruce, that the GIA identifies, they do not judge nor attempt to judge quality.
Not their job.
The qualities you are describing would limit the gems labeled with any paraiba modifier to be exceptionally rare and coveted examples, essentially ignoring the chemistry and origin of an ugly duckling.

Your approach would be analogous to limiting definitions for Mogok rubies or Kashmir sapphires to only include the finest gems with exceptional cut quality :?: Should a sapphire from Kashmir be identified as "included corundum' if it doesn't meet the highest quality standards?

Quality determination can not be defined by a lab, nor, in my opinion, should it be. That is a job for a seasoned appraiser/industry professional who uses the lab report as a tool, like a refractometer.


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 Post subject: Re: Who says what Paraiba tourmaline is?
PostPosted: Sun Dec 11, 2016 9:15 am 
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Most consumers idea of glow, is not the same as it was originally intended, when the first Batalha pieces came to light.
The "glow" and "neon" you read and hear about, is something most mere mortals have never laid eyes upon.
To have a moniker like "glow", or "neon", attached to a stone, then I would reckon it would be in the "vivid" category/grade.
If it's not graded "vivid", then can it really "glow"? It's not like a ruby with attributes that can literally make it..."glow". I see all the time, the terms "glow" and "neon" being tossed around, and used indiscriminately, for any gemstone with any amount of Cu present.

As for copper bearing /cuprian tourmalines in general...the public is getting hoodwinked, and has been for years, by paying inflated prices for stones that have some tiny, little molecules, here and there, that impart a color that is no different than other stones colored by a different molecule.
Iron can, and does, produce the same exact color as copper, as we have discussed numerous times before.
It's just that copper does a better job.... so once you cross that threshold where iron can't pump out anymore color and copper can...well...then you have a real cuprian tourmaline...a paraiba.

As for green....ha...I have a love hate relationship with green cuprians. Let me be drastic for a minute and really lay down the law.....Blue-green colors are alright, but ones that are mostly green or trending towards mostly a green hue, are not worthy of a name like Paraiba, in my opinion.
Cu+2 is the acting coloring chromophore in paraiba tourmalines. If the tourmaline was just colored by Cu+2 alone, it would be a nice turquoise blue, to blue color, that everyone likes. When you head towards the green colors, you are then incorporating Mn and Ti into the crystal lattice. When you move towards the violets and purples, you are adding Mn to the lattice. (loosely defined, of course)

So, when you are buying paraibas, then you are buying for the copper, correct?(I know levels of Fe and Mn also affect things but for arguments sake let's just say copper).
If have a green paraiba tourmaline in hand, then it had better have a strong blue component to make it worthy of the title, Paraiba, and the sttep price that comes with it.
If Cu+2 produces a turquoise/cyan/blue color stone, but you have a green stone in your hand, then where is the color the copper molecules are imparting on the stone?
Purple, red, green, yellow, etc. Don't matter. Paraiba=copper=blue
No blue...no paraiba.(I know green and purple both have blue but for arguments sake)
If you have a blue-green stone, or a green-blue stone, then you are getting some effect from the copper molecules imparting their color.
Cu+2(copper)=turquoise(blue)
Less blue/turquoise in the stone = less copper acting as a chromophore(or replaced by Fe)
Rossman says the green coloring in Paraiba tourmaline is due to Ti and Mn, some others say Iron. Green color then means, less copper imparting it's color on the stone
Copper ONLY produces that cyan/turquoise color in tourmaline.
The Green is not being produced by copper in the slightest, it's coming from iron or Titanium/Manganese.
It's really no different than a regular green tourmaline.
It has to have that blue/turquoise/cyan to be a paraiba.

If not for the finds in Batalha, Brazil, back in the early '90's, then the Paraiba/cuprian tourmaline would be a footnote in gem history.
Many a tourmaline has copper in it, but not many have sufficient amounts, in the appropriate ratio's, to give you that strong, rich hue, that imparts a vividness that many folks call "neon"/"glow".
I believe that labs are adding fuel to the frenzy by detecting trace amount of copper in stones, and labeling them cuprian/paraiba .......which technically is true .......but the amounts are so little(by weight), that either the copper is not acting as a chromophore or it's acting on the color in such a insignificant amount.

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 Post subject: Re: Who says what Paraiba tourmaline is?
PostPosted: Sun Dec 11, 2016 10:29 am 
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Welcome, welcome!

First let me say that I was misleading when I included statements about quality in a post about the GIA. I know from personal experience that the GIA does not deal with those issue in their reports. But I think there is a deeper reason for me to slip in quality concerns with Paraiba than just a misstep.

In my old edition of The Gemstones of the World by Walter Schurmann (I hope I spelled his name right because I don't have the book invfront of me.) he pauses to make an explicite statement that went like this. The term Burmese Rubies does NOT refer to the location from which the gemstones came from, but their quality. Other lesser qualilty red corundums that came from Burma, I think were just called rubies in his old fashioned world. At least that was what I thought as a kid, as I read and reread the book.

I realize that times have changed, but some old habits die hard. It is still very difficult for me to picture in my mind a pale grayish blue tourmaline being called Paraiba or fish gravel being called Burmese Ruby where the name is based only on its composition and discovery location.

Now that I think about it, I will try and give my point of view on Jason's post in another post.

Bruce


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 Post subject: Re: Who says what Paraiba tourmaline is?
PostPosted: Sun Dec 11, 2016 11:09 am 
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I just copied and reworded my post from a previous post I did on another forum. I am a little rusty, in regards to my cuprian information. If you don't use it you lose it, right? I haven't gone over any of my papers, notes, files, on cuprians, in a couple years now.
I just find it crazy that every color out there has been labeled a "paraiba" these days, just because it has some stupid Cu+2 in it. I have had brown and gray paraibas before. It shouldn't matter about the Cu, unless it acts upon the stone appropriately.

Copper imparts what color??? Like gem silica, turquoise, etc.
Attachment:
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Here are two pieces of rough that both tested for Cu. The purple is fine staying purple. Just as unique and rare. Call it cuprian if you like but until you heat it, it shouldn't be termed a "paraiba". The green one is just bland and boring.
Attachment:
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The old mine stones really set the bar. The Mauvco, Mozambique deposit was mined for 2 years before anyone realized some were copper bearing. Goes to show you, that the color isn't as "neon" or strong as it should be, or they would have noticed it right off the bat


Attachments:
heitor%2520paraiba%2520a.jpg
heitor%2520paraiba%2520a.jpg [ 85.72 KiB | Viewed 970 times ]

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 Post subject: Re: Who says what Paraiba tourmaline is?
PostPosted: Sun Dec 11, 2016 11:40 am 
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In an ideal world people should have noticed the unique cuprian-exclusive pure purple colors from Africa right off the bat, but they didn't. A lot of times people just don't know enough to make these connections even if they orta.

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 Post subject: Re: Who says what Paraiba tourmaline is?
PostPosted: Sun Dec 11, 2016 12:33 pm 
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I certainly share many of your concerns Jason, but I would like to address your comments on green and cuprian Elbaite. (and all the rest of the names you can give tourmaline with copper as a chromophore.

Now why some Paraiba/paraiba like are green is fascinating to me. Rossman in his original paper talks about the traditional cause of yellow/green in Elbaite, manganese and titanium in an intervalence change transfer reaction in a low iron envirnment. The problem with the explenation is he never found a significant about of titantium in the Paraiba tourmaline he tested. (Or green cuprian tourmaline that was tested by other researchers.) The Harmonization committy did not even include titanium as a chromophore in Paraiba tourmaline.

Significant amounts of Iron have been found in some paraiba type tourmaline from other locations, but never at Batalia. Therefor we need another chromophore to help color Paraiba/paraiba type/ cuprian tourmaline green. The color vector we are looking for is a yellow because many cuprian tourmaline have no other way to generate green, than to mix the copper blue with yellow. As you said Jason COPPER BY ITSELF DOES NOT PRODUCE A GREEN IN TOURMALINE.

For years I have proposed that the yellow vector in cuprian/Paraiba etc. tourmaline is caused by the formation of radiation induced O- hole center chromophores (color centers). Not a transition element or a combination of elements that has failed to be found or analyzed properly. The proposed color center is thermally stable up to 250 degrees C and greens from Batalia were heated to change green to blue. (It seems to me that it would be pretty straight forward to see if alternating radiation and heat to make a cuprian tourmaline go from blue to green and back again, but I don't think it has been done. If it happen at the correct temperature, a mystery would be solved)

I would like to make a few comments of the relative merits of copper blue and iron blue. I don't think, on a purely color comparison, copper is better at producing the desired color, cyan, than iron. But color is only a part of what makes all high quality copper bearing tourmaline great. I have come to call the differences in copper bearing tourmaline other than color, as its visual impact. Copper can be better than iron at producing the medium toned, vivid neon look that can not help but catch and hold the eye. I presented my belief that the mind/eye is deceived by the visual appearance of cuprian and to a lesser degree iron tourmaline, and produces a image of the gemstone that appears to produce more light (glow) than lighting conditions dictate. This visual impact of high quality copper bearing tourmaline is both wonderful and rather mysterious and without it Paraiba would not be the outstanding gemstone that it is. (High quality sea foam from Afghanistan has a lesser but similar glow like deception on the eye mind. At least it does on mine.)

Now back to green, We have a pure yellow color center to help form a green with coppers blue help in my hypothetical world. So the next step is to see if the green, formed that way, produces a better, bolder and more vibrant visual impact gemstone than iron does. I AM POSSITIVE THAT I HAVE EXAMPLES IN MY COLLECTION OF JUST SUCH A BOLDER MORE VIBRANT GREEN . (The effect is really not able to be photographed because it is a function of the eye/mind perception that the camera does not have. Most pictures of the neon glow like effect just look like the exposure wasn't correct and they are over exposed.)

A few examples are in order. I have two tourmaline with the same yellow green color by my eye and the same tone level. I did not buy either one as cuprian, but when I tested the stones with my spectrometer, I clearly saw that it was cuprian and the other is not. Does that make a different, you can bet the farm on one it. The cuprian is just a step up in visual presentation, period. I have a bi color cuprian tourmaline that has just a touch of green in the culet of an otherwise blue gemstone. Face up the round has the color of a fine chrome tourmaline but with a visual presence that far exceeds any chrome I have seen. Copper can make better greens. (with a little help from its friends and iron is not one of them)

Bruce

Did I miss something or misstep, well keep the cuprian ball rolling and call me on it. Look down.

I tried to post this and the machine said I needed to look at a new post and so I did. And I do have a little to say about Africa's blind spot in saying they had paraiba type material.

I have seen unheated Paraiba from the original find at Batalia. It certainly had an unusual purblish blue color and rich tone level, but it was not like the neon cyan colored material posted above. And without cutting it, its color was the only property that it had, that impressed me. And frankly you need to be a tourmaline collector to really appreciate how rare great blue purples and purples can be. So now to the rough from Mozambique. All the rough is well water worn and frosted, which makes then duller than the bright crystals from Batalia. And most need to be heated to see the cyan blue that is the desired color and I think shows the best glow like qualitles. On top of needing to be heated you have to cut the gemstones to really see its potiential. (It is the same with Batalia from what I have read.) One final thing. The Mozambique deposite was much more extensive and probably came from more than one pegmatite. Some of the material that came out of Mozambique at first may have been cuprian, but the production changed in both quality and quantity. The only quaity faceting material at first were large dark purple reds that when completely heated usually produced very pale aquamarine colored material. This was so poor that most of them were only partially heated to produce a nice lightly tone lavender. It was this color of tourmaline that I first got from Mavucu. I even sent my first cut stone back to Africa to show my dealer, a really great new color for me and him, in tourmaline. After the lavender, I was able to get cyan blue (remember iron) and many other bright colors. I began to think that there was copper in them, but it was not easy or inexpensive to test for copper in tourmaline at the time. And then why should I be blessed with such a great discovery? Even when I cut my first color changer I waited to send it into the GIA. After a year I got another specimen and I decided that I had to have the stones tested. So I took the hit and spent the money. And copper was discovered in the samples I sent the GIA. It was for the first time and while exciting and gratifying, I still had to pay for the report and the cost of my cutting food when sky high.

Still with all that, I have seen surface material from Batalia, thanks to Jason and it is more impressive than anything I have seen from Mozambique (in the blue green color range.) except for one piece of rough I cut. It was purchased before copper was discovered and it was the wildest piece of rough I have ever seen. It looked like a hamburger with a bright blue piece of meat and a bright green bun. I am sure that it was not heated and I thought that the colors were because of dichroism. Well it turned out to be a bi color and the green area had been a crystal terminus. The laboratory in Swizerland acturally figured that out and then told me that it was a real leaning stone from them. I wrote about it ealier and it does not contain iron. They had never seen anything like it from Mozambique. If that had been the first piece of rough out of Mavucu, I think history would have been changed. Still I am amazed that the cuprian nature of the rough was undiscovered for so long.

Bruce again.


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