Duo-blue/green, A portrait of a star in the tourmaline heaven#942

 

face up view Duo-blue/green Exceptional paraiba type blue green tourmaline from Mozambique. Deep medium sized round. pavillion view of Duo-blue/green showing neon blue around girdle deep round flawless blue green round of paraiba type tourmaline from Mozambique angled view of Due-blue-green to show side view of neon blue. Clean neon blue-green round. Angled picture of Duo-blue/green. medium sized stone.

 

The rough for this exceptional gemstone came as an after thought with the most outstanding purple piece of tourmaline I have ever seen.  (the name Duo-blue/green coming from being one of two pieces in the lot) The purple was a bluish purple, a color range I had been searching for since I decided to get back into faceting, after raising a family.  The rough was completely water worn and look sort of like a hamburger with a green bun and a blue burger.  On  closer examination I realized that one side of the bun was more pointed than the other and that side became the pavilion for a medium sized, very deep, split horizontal main, round gemstone.  As I preformed the rough, it became obvious that this tourmaline had everything going for it, exceptional color (hue), tone level (richness) and saturation (purity of color).  I also continued to see the two distinct colors, cyan blue and emerald green, in the preform and thought that the distinct colors came from the dichoric nature of the rough.

The cutting and polishing of the gemstone went well until I started on the table.  With most reasonably sized rounds the polishing of the table is not a problem.  The geometry helps and the tables are not usually that big, but duo-blue/green would not cooperate.  Hours passed while I continued to shift angle slightly and make progressive attempts to move across the table with the right angle and amount of pressure to eliminate marking.  In the end I won and the table, which is the pathway to the soul of a gemstone, came clean and bright.  Now I had a fair amount of polishing to do, to bring the stare facets back to meeting.  This can be dangerous, because if you engage a small facet, like the stars, at too high an angle with too much pressure they can fail.  And sure enough one of the stars failed.  I blame myself for not switching gears enough from polishing the table, where strong pressure had been essential to success.   After doing the best I could do to minimize the damage, I decided to finish the gem without any recutting because the wounded star really was not that noticeable without a loop.

When I removed the stone from the dop stick and got my first good look at it, I was amazed.  Face up the gem blazes a green that is an equal to top quality chrome tourmaline, with a greater amount of transparency (lower tone level) than most of the chrome tourmaline in this medium size range of rounds.   But it was when I tilted the gem off axis and rotated it, that its truly exceptional nature made itself known.  Bright cyan bubbles up from below threw the green and made me renew my praise of tourmaline.  When you flip the gemstone over and view it at right angles to the table, all you see is pure cyan in a bright, rich tone level.  With all the focus on color, I almost forgot to mention that no flaws obstruct the gems beauty.

Epilogue for a star:  I did not realize the true nature of this gemstone while I was cutting it.  After it was found to contain copper by a couple of laboratories, I was shocked to be told that the gemstone’s color display did not come about because it was  dichoric, but because it was a bi-color.  By positioning the rough to retain the maximum weight in the finished gemstones, I had retain a small amount of intense green color in the culet, that must have been the terminus of the original crystal.  When told, I saw the color  area and continue to show it off to this day.  The other pleasing thing, the laboratory told me, was the this was a great learning example for them, in their effort to understand paraiba type tourmaline from Mozambique.

I will add a graph of its absorption curve along with its picture from a European laboratory.

 

Bruce

 

 

About Bruce Fry

I was born in Summit, NJ in 1947 and graduated from Summit High School in 1966. I graduated from the Colorado School of Mines in 1970 and after spending another year in graduate school, I left to see the world of Brazil. After spending some more time discovering myself, I ended up working for the Commonwealth of Pennsylvania for 32 years as an Air Quality Engineer in the Department of Environmental Protection. I retired in 2007 and took up faceting gemstones again after a long hiatus that reached back to my twenties. I had started cutting cabochons when I was 13 and bought my first faceting machine when I was 15, but ran out of money and time until I retired.
My great love in gemology is tourmaline and the collection presented here represents my effort to get as much beauty and variety in the colors of tourmaline as I can. I was particularly lucky in being able to get unheated cuprian tourmaline before copper was discovered in gem grade tourmaline from Mozambique.

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