Strange and unique, possibly chrome green emerald cut.

Well here is another gemstone hot off the dop stick.  The rough had a natural table that was obvious and the tables outline looked rather like a “D”.  It had a moderately strong degree of dichroism with a very nice bright green a/b axis and a darker, more olive green c axis.  The c axis was so dark that I opted out of cutting an oval and decided to cut an emerald cut with possibly steep ends, to isolate the darkness.  Still as I rotated the rough and then began to shape an emerald cut out of it, I was getting signs that the long dimension of the gemstone to be was not oriented with the dark c axis.   And it was not oriented with the a/b axis.  So how was it oriented?

Since I was dealing with a smaller piece of rough, that weighed less than a gram, you have to go for retaining weigh/size or you don’t have a stone.  Therefor I preceded to rough out a normal emerald cut with an orientation that suited the efficient use of the rough.  I didn’t realize, until I cut the corners of the completely ground pavilion that the dark/c axis was oriented at 45 degrees to the sides of the emerald cut.  I can honestly say that I had never done that before.  I had ended up using a 40 degree round of facets at the keel and two more rows that were each separated by 5 degrees because the rough was darker than I would have liked. (I usually use 40 degrees, 47 degrees and 55 degrees for a three steep pavilion.)

So what did I end up with.  The material did polish well, but I had a bit of a facet failure and had to recut some of the crown.  I can see the bright green a/b, but the dark c axis dominates the stone,.  I can see the effect of the biased c axis in a lopsided flash, but I don’t know how many people would notice it.  I will have to try it out on some innocent friends without giving away the secrete.  I would also never deliberately cut another gemstone to be oriented this way.  But if I came across another weird piece of rough that could only give me a good yield by having the c axis diagonal, I would cut for weight.  If the c axis had not been so dark, the little emerald cut would have been much more interesting.

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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