An cuprian oval with mixed colors and a radioactive past

 

Blendedcolor, cuprian oval with interesting history Medium sized, blended colors controlled by flaws, oval. Unique in the collection. Mozambique material.

In the quest to completely fill the color wheel with tourmaline examples, the hardest range of colors is blue/purple.  When Africa began to produce lavenders to purples that could be slipping into the blue purple range I really tried to be on it.  After copper was first discovered to  be a chromophore in gem quality tourmaline from Mozambique ,  in gemstones I supplied the GIA,  I still pushed to obtain blue/purples at the new elevated prices.

The rough that I cut this oval from is an example of the type of material that remained available and sort of affordable, after the discovery that a new source of paraiba type, cuprian tourmaline had been discovered in Mozambique.    The rough was too included to consider heating, which I don’t do to any tourmaline and it was a moderate size.  My hope, when I purchased the rough was to mix the two colors, blue and purple, so the final gemstone would appear to be a nice medium blue/purple.  To a degree it worked, but that did not turn out to be the most interesting part of this gemstones.

For a relatively brief time, a controversy developed over the diffusion of copper in tourmaline.  Areas of color in Mozambique tourmaline appeared to be controlled by flaws in the crystal that extended to the gemstones surface and could indicate an enhancement of the cuprian tourmaline by man.  After a fair amount of “discussion and testing” work, the GIA determined that the color areas in question, that were pinkish to purplish, were caused by the natural infiltration of radioactive late stage fluids.  I had seen this effect in the rough that I cut this oval from, long before all the hoopla.  But it seemed such an obvious explanation (radioactive material in the flaws causing the reddish color to develop, that I never looked into whether it had been investigated.   I almost left the rough as a nodule with a polished window, because you could really see the effect that way, but I am a cutter and needed to see the mixing of the colors.   Included or not this gemstone’s  color mixture makes it distinctive and if you want to borrow my loop you can still see how it came to be.

 

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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