It has been most of a year since I first saw the piece of rough on the inter net and decided to buy it. It was stout water worn section of a crystal that was both dichroic and blue green. I had seen other pieces of this type and knew that the c axis was not closed, but still darker than desirable.
Now short chunky sections of tourmaline crystals that have a c axis that has a darker than desirable tone level are not particularly in demand. The a/b axis, which in the case was a wonder blue/green, is hard to accentuate while isolating the darker c axis as much as you can in cutting. (i.e. cutting an emerald cut with a decent ratio and the c axis influencing the ends) I knew what had to be done and it would be wasteful. Still it was pretty material and included enough that it was not expensive.
So I cut the piece of rough in quarters with the intent of making four emerald cuts. (The cuts were made parallel to the sides of the thick, pencil like crystal) Well there were still some bad flaws to grind out after the cutting and I would be surprised if I had much more than four squarish pieces of semi preformed tourmaline with a total weight of 6 carats left, when I dopped the first piece.
Before dopping up a piece, I saw that the c axis was not too dark anymore, in such a small piece and the a/b axis was still an attractive shade of green with elements of blue. As I began to cut the preform, I realized that it did not have the depth I needed for an emerald cut (more flaws) and the shape of the piece was getting rounder.
Now sometimes you have to go with the flow and so a droplet of color it would be. I barely had enough depth to use my usual angles of 41 degrees in the mains on the pavilion and 40 degrees on the crown. Still I was within a few mains of finishing the crown (I still needed to polish the breaks) when the polished surface of the main I was working on was torn asunder.
There is not a lot of room to regrind the facet on the breaks of a standard round brilliant in my world. Still it had to be done to save anything, considering the amount of weight loss that had occurred. After successfully regrinding and polishing the main, I moved on to find that a second main had its polish torn from its surface. Well that was a find affliction and I needed to push myself to regrind another facet and polish it up very lightly. What was left after the regrinds was a stone that needed a lot of fudging. Now adjusting facets is something that my machine and I do very well and after too much time, the 5 mm stone was finish. (one of potential 4 from a piece of rough that weighed about 15 carats.)
Now the reward for all my work is an interesting gemstone. The slightly bluer a/b takes up its alternating quarters in a bright clear fashion. While the c axis (a nice grass green), which is only a slightly darker tone than the a/b shows a lack of transparency that I have seen in other tourmaline at times.
This whole exercise was brought to you by a market for tourmaline rough that is getting worse as I write. The latest news in from Africa signals the death knell of my hopes of getting anything really interesting and productive anytime soon.
Picture to follow, but you will have to look close to see this one.