It is always nice to get a delightful surprise and when it turns out to be a great new tourmaline, than that merits a post of progress with the collection.
The piece of rough I gotten from a friend did not look that promising. It was a completely water worn pebble that did retain some vague crystal surfaces. It was dichroic with an darker orange c axis and a golden yellow a/b axis. I have had similar pieces and I love yellow and orange in tourmaline, but with the rough being so frosted they rather looked brownish. Brown really takes the edge off yellows and oranges, but that wasn’t the major problem with the rough. The crystal had split sometime in the distant past and so orienting the gemstone with its table perpendicular to the c axis (across the end of the pencil) was not practical. I would have probably oriented the gemstone that way, because then I would have had a uniform color and probably brighten up the orange c axis color with the mixing in of the golden yellow a/b color. This left making some shape that would have to deal with two significantly different colors face up. Rounds cut with this orientation can get a bit kinky, but that is what won the debate. The rough wasn’t very thick and even though I lost the corners of the crystal, I thought I would get a decent yield.
Now my first step in cutting a round is to preform a shape, pretty round I hope, that is easy to center. I really do not try and make the perfect preform since the bulk removal of material while faceting is not a problem with most of the tourmalines I have worked on. And if you over grind an area of the preform and have to reduce the size of the finished gemstone it is indeed a sad day.
I usually set my protractor for between 40 to 42 degrees when cutting the mains for a standard round brilliant with tourmaline (I really have cut other material) with the vast majority being at 41 degrees. I generally use my coarsest lap, a well broken in 320 grit in grinding the culet while being sure that I really cut each nascent main completely. I will touch up the culet later, but for now I want to be sure that the preform is reasonably level and centered. As I ground down the preform I notice three things.
1, The stone had to be slightly re-centered.
2, The colors were better than expected.
3, A crack that had either formed while cutting or was there in the rough at the beginning and I missed it. It wasn’t bad as it only extended about half way down the depth of the rough from the culet side.
Now rough like this has probably been naturally irradiated and I find that it can be more prone to chipping, rather like hot pink tourmaline. And this gemstone developed a tiny crevice on one of its mains just down from the cult. It would probably have no impact on the beauty of the finished gemstone, except if it failed and then I would have a missing culet. I polished the mains to the sides of the flaw, but it was not coming out without too much damage to the symmetry of the round. So I completely recut the pavilion. Hey I am an amateur and this is suppose to be what I want to do to have fun. So I started to have another round of fun with the cutting and polishing the pavilion again (it really did polish beautifully) when I noticed that the basically vertical flaw I had noted as the number three item in the gemstone, had traveled deeper into the gemstone. This is most unusual and I really only have had experience with blues from Namibia with the same problem. It may be related to the heating of the rough.
I finished the pavilion and transferred the gemstone, after deciding that I would not recut the gemstone because of the flaw. I was finishing the mains on the crown when it felt a thud and the stone rolled a little on the lap. I cut a little more, but I knew that the stone had failed. A beautiful conchoidal fracture had taken out the lower part of one of the crown’s mains and a part of the girdle. It was rather temping to move on and mark one up as lost, but the color had been looking good and I don’t have a lot to work on. And so I went threw all the steps again as if the semi-cut gemstone was a preform until I began cutting the crown. Now I had been very aggressive in retaining as much of this round as I could and it turned out that in redoping the piece I had rotated the round about 90 degrees from the original orientation. Making a standard round brilliant with the same angles on the crown’s mains and over the pavilion’s mains, was not going to work. I did not want to drop the crown’s mains, so I did something I had never done before. Now this isn’t really anything special, but I had never cut just two rows of sixteen facets each on a round’s crown before. Well I had just enough material to complete the round and have a flat facet over each main in the pavilion. And even better then that, the rather strange vertical flaw was gone and everything polish up great.
As I heated the stone in a pan of water, up to boiling, to release it from the epoxy and washed the gem in alcohol to clean it, I knew that I had something special. Remember how brown really kills oranges and yellows, well without it, they really shine. And I could see that this gemstone had come clean from behind the veil of brown and sparkled brightly even in the terrible light of my overhead florescent light in the kitchen. Its unblinking yellow eye was in good contrast with the darker orange quadrants and the pair flashed together in perfect harmony. There are still a few chips on this fragile flower, but it has a sound girdle and an intact culet. I think that it likes its new home in the little plastic storage box where it will shine and flash as long as I have it. Oh it weighs 1.88 carats.
I think that I better keep working on my technique before I try and make any money cutting, since it took me more than an hour to finish this modest round!