14k yellow gold, tanzanite and diamond ring. Round brilliant cut diamonds. VS-SI clarity and G color diamonds. Tanzanite is a trade name that was first used by Tiffany and Company for gem-quality specimens of the mineral zoisite with a blue color. The name tanzanite was given because the world's only known tanzanite deposit of commercial importance is in northern Tanzania. The name reflects the gems limited geographic origin. The mines are all located in an area of about eight square miles in the Merelani Hills, near the base of Mount Kilimanjaro and the city of Arusha.Although nearly all of the worlds most popular gemstones have been known and used for hundreds of years, tanzanite was not discovered in commercial quantities until the 1960s.