New Mineral Named After GIA’s John Koivula
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 Post subject: A bit of Salada? A Brazilian tourmaline connection.
PostPosted: Mon Jun 10, 2019 1:00 pm 
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Joined: Thu Sep 25, 2008 10:33 am
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I must confess that I have cut very little Brazilian tourmaline. With tougher environment regulations and the depletion of alluvial surface deposits, Brazil doesn't dominate the tourmaline world like it use to. I think it is to the point that Brazilian dealers regularly buy African rough tourmaline and take it back to Brazil to be processed and sold as Brazilian.

I had read that while top quality tourmaline from Brazil was scarce, a low grade of faceted tourmaline called salada (salad) was abundant. This salada was native cuts that were focused weight retention and came in all the colors presently being found in Brazil. Since my principle interest in getting Brazilian material was color collecting I decided to try and get some salada. I made contact with several deals, one of which was an American expat. I explained that my interest in unusual colors of tourmaline with a particular interest in purple.

The American expat was quite frank about a lot of the tourmaline in Minas Gerias was African and the importation of rough was essential for the Brazilian gem industry. Still she was willing to contact her connections and see what she could find. She was not successful in getting, specifically, purplish tourmaline because the sellers were concern that I knew something they did not know and I was taking them. Be that as it may, I think the real reason is that they want to sell me a large, complete, lot of salada. It would have been significantly cheaper per carat, but much of it would have been too small to recut and not of any real color interest. At leased that was a second dealer that I ended up buying a fraction of a lot of salada from. He reluctantly sold me a selected group of stones. I was not really impressed with his selections, but I did get a few non cuprian purples combined with mostly material of little interest. I paid the price and moved on back to Africa.

The salada turned out to be reasonably symmetrical stones that were papered with facets placed for weight retention. The facets were neither very flat or well polished. In other words "native" cuts. I didn't even get a very good, yield when you consider that I was starting with a better preform than most rough pebbles. Of course I was using good angles and a reasonable ratio between the thickness of the crown to the thickness of the pavilion.

While I was looking for my next project in my severely depleted stock of tourmaline rough I found one of the old salada pieces. It was a pale pasted bi color of pink and yellowish green. It was cut in an emerald cut that was both significantly included and dull. I could see why it had not been recut even though it could make a carat plus emerald cut. Without a lot of choice I decided to keep busy and recut it.

As I cut into the heart of the emerald cut I realized that I was doing more than just placing correctly angled facets, I was removing a significant amount of inclusions. In their quest to get the "most" out of the rough, they had left too much "skin", an outside layer that is found on a lot of tourmaline and is flawed many times. It began to get more interesting when I was able to balance the areas of the two colors in the developing gem. Finally the remaining inclusions only broke the surface in a few places on the pavilion and the polished table turned out to the pure path to the soul of the Brazilian sweet heart. Yes it turn out to be a nice bright gem of most of 2 carats. It is included, to the degree I would expect, in a Brazilian tourmaline of this type and was by far the best gem I got out of my one time, Brazilian, adventure.

Bruce


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 Post subject: Re: A bit of Salada? A Brazilian tourmaline connection.
PostPosted: Mon Jun 10, 2019 3:26 pm 
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Pictures???

Or as they say, "If there aren't pictures, it didn't happen!"

:wink:

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