Finally finishing a couple of included pieces of blue green tourmaline

I am not sure that would have even purchase these two pieces of rough in the “old”days.  They did have nice colors in the pictures on the internet, but they were at best semifacet grade and were short sections of water worn crystals.  The colors came from the rough being strongly dichroic and the grade came from easily seen inclusion that would probably be distracting (not good) in the finished gemstone.  Still I needed something different to work on and their darker green c axis and very nice blue/green a/b axis looked promising.

The first piece of the rough I cut in a “normal” fashion.  That means I went for the best gemstone I could get out of the rough.  I split the crystal section and ended with two ring sized stones that are still included, but with none of them flashing too much with the stones face up.  Still the end product was less than I had hoped for.  I had to cut the stones with the c axis perpendicular to the table, which produced a wonderful green color under the incandescent light that I work with, but when it went outside the stone closed up excessively.  More so than I have seen in other dichroic blue green tourmaline.

So what do I do for an encore?  I decided to ditch the idea of getting anything very large out of the rough or for that mater anything very valuable.   I decided to slice the short crystal section two times which lead to four pieces that I preformed into two small rounds and two emerald cuts.  Now the water worn crystal rough was only about 6mm thick and it did have significant inclusions.  The small rounds turned out OK since they were so small, less than 1/2 a carat that the darker c axis had little adverse effect on the.  In facet it became an asset.  Still I had not been able to really appreciate the a/b axis excellent color as much as I would have like to, since the green c axis dominated.

Now it came down to the two emerald cut preforms to finally show me the best a/b color that the rough had.  But the first preform suffered from the poor corner syndrome and ended up being cut as a round.  The final emerald cut preform had the darker green c axis color isolated in the ends (I didn’t use steep angles in the ends to really minimize the c axis color because it is open and pretty in such a small piece.) so that I would get as blue/green a gemstone out of the rough as I could.

Last night I finished the emerald cut and it is a flashy gemstone even though it is a bit crinkled from internal inclusion that are not obnoxious to my eye.  The a/b color which is a nice medium blue green does shine also (especially under incandescent).  So I think I did well, but with a weight loss that was exceptional bad.  And the a/b color, while very nice really does not measure up to its appearance in the rough because the gemstone is so thin.  Still it was worth doing for the challenges it presented along with a story and six stones that will not completely disappear into the collection.  The last emerald cut does have personality and the large ring sized stones still leave me wondering why they get so much darker in natural light than incandescent.








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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