1ct Three Stone Tanzanite Drop Earrings In Sterling Silver Tanzanite is part of the zoisite group of gemstones. One of the most recent gemstones discovered, tanzanite was discovered in Tanzania in 1967. The most popular color is a pretty blue, with a purplish hue. Tanzanites are heat treated to a temperature of 400-500 degrees Celsius, which eliminates brownish and yellowish tints. All tanzanites that SuperJeweler sells are heat treated to enhance the blue color.