Tanzanite is an exceptionally rare and highly prized variety of the mineral zoisite, found exclusively in a small area near Mount Kilimanjaro in Tanzania. This remarkable gemstone displays intense pleochroism, appearing different colors when viewed from various angles—typically shifting between deep blue, violet, and burgundy hues. Discovered only in 1967, tanzanite is considered one of the world's rarest gemstones, being 1,000 times rarer than diamonds, making it a coveted collector's stone and investment piece.
Specifications:
- Color range: Deep blue to violet-blue, with some stones showing purple, burgundy, or bronze flashes depending on viewing angle
- Hardness: 6 to 7 on Mohs scale (moderate durability, requires careful setting in jewelry)
- Origin: Exclusively from the Merelani Hills near Arusha, Tanzania—the only known source worldwide
- Sizes: Available from small accent stones (under 1 carat) to rare large specimens (over 10 carats), with most commercial stones ranging 1-5 carats
- Shapes: Primarily faceted cuts including oval, cushion, emerald, and round brilliant to showcase color and pleochroism
- Clarity: Ranges from eye-clean to included, with higher clarity specimens commanding premium prices
- Special properties: Strong pleochroism (trichroic), vitreous luster, and heat treatment commonly used to enhance blue coloration
- Rarity: Extremely limited supply with mining expected to be exhausted within decades
