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 Post subject: The story of a stone.
PostPosted: Tue Feb 26, 2019 3:14 pm 
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Joined: Thu Sep 25, 2008 10:33 am
Posts: 840
Location: Mars PA
I believe the story goes that the long term lapidary collects/hoards so much rough material that he can never begin to cut all the material he has. That has not been the case with me. I had opportunities to purchase lots that would have kept me faceting for many years and still have pieces I really did't want to cut. I passed most of them by and focused on selected interesting individual pieces. Sadly all those have been cut and I am now looking at the residuals from lots long ago.

In an old beaten up plastic bag I found a sawed section of bluish crystal. It was dichroic and did not seem to have a great deal of transparency down the c axis. When I looked at the other end of the section, I could see the classic triangle of much darker blue, centered in the crystal's cross section. I have seen similar bands in tourmaline many times. The darker center was probably the reason I had not cut this 1 gram piece of rough a long time ago. On close inspection, I figured I had a shot at a round with the c axis perpendicular to the table and away from the dark center, that would not be too dense.

The pavilion cut quickly and polished well, even though the dark triangle was mostly gone, this was not going to be a really sharp stone. I had to be careful with the crown, because I had ground the piece down as much as I could, to not only get away from the darkness, but also, keep some radial flaws from weakening the stone too much. As I began polishing the table everything was going well, when the polished edge of the table was torn by the lap. It was more than scratches and too deep to polish out even on only a six mm stone. This is unusual, but not unheard of with my style of polishing. With some care I finished the gem and looked at it with light from the north. In a moment I realized that this gem was visibly different. A tourmaline that is different, even if it only a subtle difference is interesting to me. So rather than eat lunch, I set up my spectrometer.

What came up on the screen is why I am writing about a rather dark greenish blue round that does not have very good clarity. The absorption curve has some peaks I have never seen with tourmaline before. Everything about the rough indicated tourmaline to me and the absorption graph could be of a different exotic tourmaline, but more testing will have to be done. Anyone care to hazard a guess? My photograph that did all the pictures on my site brucefrytourmaline.com is available again, so I may be able to post a picture, but I don't think that it will help much.

Now I stand surprised and humbled by a tourmaline, from the bottom of the barrel, or a want to be. Either way it keeps me cutting and writing.

Bruce


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