Tanzanite is one of the rarest gemstones on Earth, found in a single location on the planet — at the foot of Kilimanjaro. This blue-violet variety of zoisite is celebrated for its phenomenal pleochroism: as the stone is rotated, it shifts in hue from deep sapphire blue to rich lilac and purple. A "one-generation gem" whose reserves are rapidly diminishing, tanzanite has become a symbol of exclusivity and refined luxury.