This is one of the most important gemstones in the collection. It weighs 13.90 carats and is the only pear shaped stone in the collection. A friend of mine designed the cut to maximize the yield from the rough and the optical properties of the finished gemstone. The rough was deeply water worn as is all rough from Mavuco Mozambique. It was unusual because the rough was flawless and uniformly stained by iron. The staining caused the rough to look greenish rather than the more desirable cyan blue.
The finished gemstone is flawless, has a good visual impact (neon brightness) and a fine polish. The only problems I generally have with cuprian tourmaline from Mozambique is under cutting during polishing on facets perpendicular to the principle axis. The cut has more flash in the pointed area of the gem, which is expected in a pear shaped gemstone.
I have tested the gemstone with my spectrometer and found the characteristic twin absorption peaks in the infrared of copper. I also have a nice picture of the gemstone along with its absorption peak from a commercial laboratory that I will attach to the bottom of this post.
This was my greatest bet on a single piece of tourmaline rough and I won with a large clean cyan gemstone with a nice neon glow from copper.
The twin peaks of absorption in the following graph that show the gemstone contains copper are at about 700 and 900 nm. Iron in tourmaline can produce an identical, cyan color, but it only has the 700 nm peak. The 900 nm absorption peak is outside the visible light range and therefore can not effect color.