An Oval by the Numbers

It has been a bit, but I finished a tourmaline gemstone today that is worth commenting about.  The rough was a pretty average piece of dichroic brownish gold that had be reduced significantly to eliminate a major flaw.  And I decided to cut an oval with a ratio of 1.5 which is as extreme as I usually cut.

The rough was probably from Zambia and I have cut quite of bit of material that is similar.  It both cuts well and polishes well.  The pavilion worked up well and the I experienced  only a little undercutting until I reach one of the ends.  I was with one facet from finishing the pavilion when a C axis polishing problem ripped the facet.  With my use of alumina/vinegar and a stationary lead/tin lap I find that the c axis can be completely different than polishing the a/b.  In this case I think that I let the waste build up too much on the lap and with a more fragile and reactive c axis, the facet failed.  I ended up having to regrind the facet with my well worn almost dead 3000 grit lap and repolish about a quarter of the pavilion.  It all went well and the transfers went well so I was in a very good position to finish the crown.  Now I really don’t use meet point except to get a good shape for my girdle.  But I do use the suggested angles for a meet point design, or at least I try to.  With this stone, something happened that has never happen before on any of my ovals.

I CUT THE OVAL’S CROWN WITHOUT MAKING A SIGNIFICANT CHANGE IN THE MEET POINT ANGLES IN THE PATTERN AND THE CROWN CAME OUT WELL.

I never expected to see it since I adjust many cuts by eye as a work up an oval.  But there it was an oval by the numbers.  (I don’t use the meet point cutting sequence) I never expect to see it again.  I hope to get Jeff to take a picture and I will attach it to this post.  (I have another tray to have photographed), but it is not an exceptional stone unless you can tell that I did it by the numbers.

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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