corundum, Sri Lanka.12, gems

Double phenomenon in sapphire. The 21.53-ct star sapphire shown in figure 6 is unique in that it also shows a distinct change of color from bluish purple in incandes-cent light to blue in fluorescent light. The natural star sapphire, an oval double cabochon that measures 14.52 x 12.88 2 10.87 mm, is from Sri Lanka.