In the beginning there was only a primeval need to crave all the colors of the rainbow and more in gemstones. I had not cut a single gemstone in thirty years and I was on that newfangled thing called the inter net. As more of the world of tourmaline (yes, gemstones soon became tourmaline) was revealed to me, than ever before, I realized that I would never have a decent collection of tourmaline unless I started cutting again.
At first I cut a bit of everything, as I kept widening my world of color in tourmaline. My color quest soon focused on orange and purple tourmaline. I am not talking about golden oranges and reddish purples, but true oranges and purples on the bluish side of heaven. As it developed, yellow without a brown or green overtone, turned out to be another difficult treasure.
In time the color niches in the growing collection of tourmaline were filled in with various sizes and tone levels of finished gems, with the notable exception of the semi mythical blue purples. I mourned that Paraiba, which was both unheated and affordable had passed me by, unnoticed, during a time of heavy involvement with my growing family and job. Would I ever get an opportunity to cut such purples, to complete the color wheel and find a modicum of complete color satisfaction?
Then a trickle of purples began to emanate from Mozambique. I purchased everything I could and because of my perseverance I discovered a new variety of tourmaline that is a reverse Alexandrite color changer. It goes from purple in daylight to bluish in incandescent light. At the same time that the Gemology of America confirmed the reverse color changing characteristics of “Laurellite” the name I gave the new variety of tourmaline, they discovered that it contained copper as a significant chromophore (along with much more common manganese) for the first time in a tourmaline from Mozambique.
The purple tide crested with the purchase of an eye clean pebble of vivid purple that weighed forty carats. The sixteen plus carat gemstone that was cut from the pebble is still the ultimate purple in the collection and always will be. There is no way that I could afford such a piece of tourmaline, after it was discovered to contain copper and had the potential to be heated to produce the very expensive cyan blue paraiba like tourmaline. Even with the greatly increased cost of copper bearing purplish tourmaline, I did not stop buying purple tourmaline. The rough was generally paler and more included, but still very attractive in my eyes. Besides in was both different and helped complete the color wheel.
The gemstone that I just finished and the reason for this post is a product of the after glow that emanated from the discovery of copper in tourmaline from Mozambique. It was not inexpensive because of its rich vibrant purplish color and copper content, but its clarity which was a lower cab grade, kept its costs manageable. Despite its low clarity grade, it appeared to have good crystal in the inter net picture and I put my money down. I can return the rough if I am dissatisfied, but I almost never do (it is a hassle) and even with that assurance this is a big gamble for me.
I purchase the rough about six years ago and I am just finishing cutting it in 2014. (I actually finished two gemstones from the rough, but this oval is the superior gemstone to the recently cut round.) It is exceptionally rare for an exciting piece of tourmaline not to be cut much soon. Waiting and hoping for research on the piece is the reason for the delay. I felt the research was called for because the vivid purple had a bluish side that appeared to manifest itself in a thick skin of bluish tourmaline that did no change color and a heart of purple that did. (Still a Laurellite, but a rather mixed up one.) I sacrificed a significant amount of material to have a thin section made, which has been lost with just a little preliminary testing, and hoped that waiting and maybe wasting a little more would help explain why only some unheated paraiba like tourmaline is Laurellite and others are not.
With little to cut and a growing frustration, the dam finally broke and I cut the remaining piece of rough into two preforms. As I ground down the rough, I was pleased to see that not very much good material had been wasted to make the thin section. A flaw/break down the center of the long axis of the rough had to be removed. Either grinding it down or slicing a side, would have removed (and did) more than making the slice did. Also the rough turned out to be strongly dichroic and grinding down the edges of the rough did not remove that feature of the rough. ( I had been afraid that the bluish non color changing skin of the rough would be lost in cutting and I think it was. Still the skin could have been just an effect of the tourmaline’s strong dichroic nature.)
The final cutting of the oval preform turned out to be a wild adventure. I had to continue to make the preform thinner to get a shot at polishing a table without obvious cracks. After preliminary cuts on the pavilion, I realized that I needed the thinnest design possible to both take care of a badly flawed keel that had fallen apart while grinding and bring down a side of the keel that was badly damaged. I held my breath as I cut the knife edge that is the prominent focus spot on the pavilion and I was able to polish it with significant chipping. Then the stone turned around and chipped badly on the side edges of keel which necessitate re-polishing one side edge and the surrounding facets. A few residual flaws did fall apart, but since they were on the pavilion, they would not be a structural problem or distracting. The clean facets polished beautifully, but I could tell that the tourmaline interacted strongly with the polish and was relatively fragile.
I was very careful with the cutting of the crown because I did not want to have to remove any more material than needed to make my meets threw polishing. There was a particularly strong possibly of the tearing of the facets that were oriented on the c axis. The table being the problem child as usual. Well with all my hopes riding on a clean table, the polish tore the (unknown expletive) out of the mostly finished table. I had also seen indications of the traces of fractures breaking the nascent tables surface. Well here it goes again. I ground down the table with my extremely well worn 3000 lap and was bitten again badly. Now I am beginning to think that I may have to try diamond to polish the table and I am glad that I decided to make a step cut crown, which is easier to manage with recutting the table. Still I have to make this work soon and I have the rest of the day to try (The stone is only about two carats in size, 10.4mm by 7mm). Now I am always optimistic after a regrind and the polishing chemistry was right for success, but I felt that it was only a matter of time before the table failed again. So I needed to do a passable job and quit. No messing around on some less than perfect spot, if it did not mater in the final beauty of the stone. It is part of the game when you cut included gemstones.
As the flaws crept bigger, the polished surfaced did not fail with the lightest touch I can manage. I believe the table is the pathway to the soul of a gemstone and this purple beauty does not have a perfect path, but it was the best I could hope for in such a sensitive, included piece. Fortunately the rest of the crown’s facet were not impacted by fragile flaws and only wanted to under cut (especially on the row of facets close to the c axis). It took time, but the undercutting was minimized.
So what do I have, from the largest rich purple piece of rough that I have been able to get short of the ultimate purple that cut a 16.66 carat round. A bright vivid purple oval and a similar round (not as internally clean) that shows both of its dichroic colors (purple/bluish gray) in natural light and goes completely bluish gray in incandescent light. They are truly unique in the collection and I would still like to have research done on them. (Nothing destructive thank you.) In the oval, there is a minor white spot in one end of the oval, but the body of gemstone only has a maze of very fine hairs that permeate it (The painful flaws do not impact the stone). The very fine hairs are not altogether unpleasant since they flash in the sun rather like in rutilated quartz and dwell in a fine crystal matrix that has a clean bright look. I am pleased, it is probably the last of its kind for me.