No. 701N: Oval Cut, 1.23 ct., VS, 6.9 x 5.8 x 3.6 mm, $135.30, faceted by a Native Cutter

Shown above is an interesting blue-green sapphire from Montana. Many natural sapphire crystals contain tiny included crystals of the mineral rutile. The tiny inclusions cause the crystal to look cloudy. Long ago the sapphire miners in Ceylon and Asia learned that if they heated this ugly milky white sapphire (called gueda) to a very high temperature, the rutile inclusions would dissolve into the sapphire crystal lattice. Under the right heating and cooling conditions the clarity of the heated sapphire could be greatly improved. Furthermore, the color of the original light milky-white sapphire was often changed to a beautiful deep blue. The majority of the blue sapphires on the world gemstone market have been heat treated to improve both the color and clarity. [It is an industry fair trade practice to disclose this enchancement/treatment to customers purchasing such stones]

Sapphire from Montana also contains rutile and the color and clarity of Montana sapphires can also be improved by heat treatment. The above stone has been heated. In this case the rutile inclusions were not uniformly distributed throughout the sapphire. When the rutile dissolved, it caused the formation of blue color bands in the cooled crystal. This explains the mottled blue-green color of this gemstone. It should be noted that color zoning is also common in completely natural sapphire; just the way nature made it. This Thai-cut gemstone is reasonably well crafted. The proprotion, meetpoints, and polish are all relatively good. This gem would work well in a ring, pendant or pin.

Return to inventory list