Tanzanite is a pleochroic stone, a transparent version of the mineral zoisite, and may range in color from blue to dark violet, albeit in recent years a transparent green tanzanite was also discovered.
Tanzanite comes only from Tanzania. Tanzanite is fairly brittle and must be handled with extreme care. It is typically safer in earrings and pendants than in rings.
Nearly all tanzanite is heat-treated to improve (or sometimes even create) the blue and dark violet colors and simultaneously to drive away the undesirable yellows and the browns.
