I have just spent a bit of time trying to orient this rich green gem with it c axis. With a gemstone that weighs 19.54 carats and is distinctly dichroic, that should not be too difficult. But perhaps I am getting ahead of my story,
When I first saw the piece of rough that was to became this gemstone, I was not impressed with its shape. It was rated triple A, but the odd shape would limit yield and got me a discount. The pebble was also completely water worn with not residual indications of crystal facets. I started out with a round in mind and as I removed the frosted exterior I could easily see the browner green (olive c axis) and the really great bright rich green of the a/b axis. The c axis had a somewhat higher tone level then the a/b, but its main fault was a lack of transparency and a less desirable color. I kept wanting to orient the c axis at a 45 degree angle with the table. This way I would have a round with a face up view that would be a mixture of the a/b and c axis colors and areas of both colors around the girdle. Thinking about it again, I probably accomplish what I set out to do, but it was probably the most difficult clean tourmaline I have ever had to preform.
So now what did I get for all my effort. The standard round brilliant with 12 mains on both the crown and pavilion, comes in at 19.54 carats. It has thick crown with 41 degree mains on the pavilion. Even with a full thickness gemstones, some of the areas of the round fire up quite nicely under moderate light and really show off the a/b color, but the table is pretty much dead. As I play with the gem by dipping it and rotating it, the rim dances and the denser area under the table opens at steeper angles. It can be made to dully flash in a very modest way when the gem is close to face up. What you can see of it, the c axis color dominates under the table. Now having a dull empty volume under the table is not the greatest, but its lack of response, keeps the less desirable color of the c axis from dominating the gemstone, while the great a/b color and tone level, dances. In the real world of distant views and moving gemstone that certainly makes an interesting and pretty gemstone. It is unique in the collection.