I am writing this on February 2, 2014 and the availability of rough tourmaline has never looked worse in my opinion. Between wars and competition from commercial processors of rough for mainly Eastern buyers, the amateur cutter, like myself, encounters few pieces of quality rough at barely affordable prices on the market.
It is against this background that I proudly present a stone, I just finished cutting, that is a fine addition to the collection. The rough’s picture on the inter net grabbed my eye and when I read that it was tourmaline, rather than golden beryl and came from Northern Mozambique, I knew I had to try and get a piece. (there was more than one piece of rough available from the same source)
I mistook the rough as a piece of beryl because it had sharp faces and had obviously never been worn in a stream. It also had had its terminus clipped off. Bright crystals of tourmaline that were mined from a pegmatite in Mozambique are certainly the exception to the normal water worn condition of rough tourmaline from there. And its pale a/b axises golden color is far more common in beryl than tourmaline. On top of all that, it weigh in at over 18 carats, which is a much more common size for beryl than tourmaline. I could not see the c axis in the picture, but it was described a champagne.
When the rough arrive, I discovered that the rough crystal was mildly dichroic and had more damage from clipping than I had hoped for. Still the crystal had almost parallel sides and did not have any deep striations. It had a good depth for its width and would produce an emerald cut with an exceptional amount of retained weigh (yield). Also to its credit was a color that would probably not be duplicated by even a small tourmaline in the collection. The yellow to orange color in tourmaline is certainly much more common in tourmalines from Eastern Africa than the rest of the world. But even with my good access to tourmaline from this area, yellows are still not well represented in the collection. At least this is for yellow tourmalines that are not weighed down by a brown or green modifiers. And this tourmaline never showed any inclination of being a common yellow green or browning out.
The hardest part of cutting this crystal, which was practically preformed for an emerald cut, was picking the side for the table. The crystal had great symmetry, but both suitable sides for the table had a crystal edge that was not centered between the sides of the crystal. I decided to try and let the cutting of the pavilion take care of the clipping damage. This proved to be both a plus and minus when it came to retaining weight. One end, that had been clipped, had a bad squarish chunk missing, which I certainly did not miss in my evalulation, but behind the missing section a flaw had propagated parallel to the nascent table. This discovery was a bit disheartening, because if I had used the other side of the crystal for the crown, I would not have lost as much material. Still, we are just talking about a few millimeters and I was to find another unexpected development. Even though the the crystal looked so bright and crisp, there was an area on the side of the crystal, I used as the pavilion, that developed a significant conchoidal fracture. It was most unusual and I think it came from mishandling the rough.
Now emerald cuts are deep color cuts and when you loose depth in a tourmaline crystal because of flaws it generally means that the width of the gemstone has to be reduced to maintain good angles. So the tension continued to build as I ground out the conchoidal flaw. The facets on the long sides of the gemstone’s girdle became thinner and thinner and I began to wonder if I would have to put in the first row of facets on the crown at an angle of less than 40 degrees. I have certainly done that before, but I prefer a high crown, especial with such a lightly toned gemstone. As I ground out the fracture, I realized that while I would had gained some yield from switching sides in grinding the table, I would have lost in yield on the crown when it came to removing this very inconvenient fracture. So I did about as well as I could have hoped with yeild on this tourmaline.
After doing a minimum of fine grinding with my well worn and half dead 3000 grit lap, I was ready to polish. It polished like a dream. At times I wonder about the years of work I put into develop my polishing technique for tourmaline. The use of a stationary lap with a mixture of chelated alumina and vinegar is hardly revolutionary, but it is well suited for my disposition and the limitations of my platform faceter. I still have my difficult tourmalines, but this extremely pure yellowish tourmaline never rebelled and its table must have been one of the easiest ones ever polished. I had to be careful to get any deeper grinding damage completely gone, because it polished so fast. It rated right in there with medium to light pastel pink from Nigeria as the easiest tourmaline to polish for me. It ended up being a real headlight of brightness in a world that does not appreciate emerald cuts as much as they should be, when well cut and polished. (That is both an opinion and editorial comment)
Now its finally time to talk about the finished gemstone that is pictured below (when I get Jeff to take the pictures). It is flawless and weighs 8.4 carats, which represents a yield of 46 percent. (I was just able to finish the crown with three rows of facets at 40 degrees, 30 degrees and 20 degrees.) As I have said it is a very bright gemstone. It has a medium tone level and is mildly dichroic in some lights. Now there I go again talking about different lights, but it is important. I even waited a few days to post about this tourmaline because I was not able to evaluate its color in the glory of a winter’s sun. Well now I have and the darn thing shifts in color on me.
I love dynamic color and tourmaline never fails to amaze me with its endless cascade of color, but it leads to a lot of writing and pictures. And even then you have to see the gemstone to really appreciated it yourself. My first view of the good sized emerald cut was under the terrible florescent lights in my kitchen and a new squiggly florescent light I use as a replacement for my old incandescent light. Both lights showed a pure bright yellow without dichroism. But this was not the look I was getting under my incandescent work light over the faceter. There the color was more orangish and the c axis was definitely richer colored than the a/b axis. When dawn woke up gray and dreary, I really did not know what to expect. Cloudy skies are said to be very bluish, but the emerald cut remain on the orangish dichroic side. I was ready to write, but patience is a virtue and we do see the sun occasionally on Mars (my little town in Pennsylvania) during the winter. Well yesterday the sun struck and I was ready. I took the emerald cut out for a walk and while walking backwards I was rewarded with seeing a bright pure yellow emerald cut that is not dichroic. When I did not have direct sunlight on it, it was a more complex orangish yellow, that I think matches the color of 100 per cent pure Niagara grape juice that I use to drink a lot of. (Champagne is also probably a good name under some lights, but since I don’t drink alcohol, I have little experience with it.)
I am smiling to myself, (my cat is asleep after a hard night) because you’re going to have to see this one to believe this is tourmaline. I would never guess it was a tourmaline if I didn’t know it. It might be a topaz or beryl or one hell of a sapphire. The question of what the tourmaline looks like, when I get a different one, just supports my contention that tourmaline is the “Jester of Gemstones”. I can play tricks on you and it is always entertaining.
picture to come.