Tanzanite is a blue-violet variety of zoisite (Ca₂Al₃(SiO₄)₃(OH)), known for its striking color that ranges from deep blue to purple depending on the lighting and viewing angle. It has a Mohs hardness of 6 to 7, making it moderately durable but requiring care in jewelry settings. Tanzanite is found exclusively in Tanzania, near Mount Kilimanjaro, making it one of the rarest gemstones in the world. It is often heat-treated to enhance its vibrant blue hues by reducing natural brownish tones. Due to its beauty and rarity, tanzanite is a highly sought-after gemstone in fine jewelry.