corundum, sapphire, East Africa, Kenya.12, inclusions.5, gems

A brief inclusion study was done on a small sampling of Turkana sapphires provided by Ted Themelis. Perhaps the most distinctive feature throughout the lot of approximately 30 pieces was a slight cloudiness, or girasol," if you will. While in reflected light the stone might appear blue or green, in transmitted light an oily yellowish "diesel" appearance was seen (see Figure 1). This was found in virtually all specimens, except the one piece which had been heat treated. Heat treatment removed this cloudiness, as well as improving the color, suggesting that the cloudiness may be exsolved Ti and/or Fe compounds."