Tanzanite

Tanzanite is the blue and violet variety of the mineral zoisite. It is one of the rarest gemstones on Earth, found only in one place: the Mererani Hills of Tanzania. It was discovered in 1967 and named by Tiffany & Co. after its country of origin. Naturally formed tanzanite is extremely rare and formed by metamorphic activity.

Formation & Geology

Tanzanite is found in metamorphic rocks (gneiss) in the Mererani Hills. It obtains its color from trace amounts of vanadium. The rough crystals are typically trichroic, showing blue, violet, and burgundy colors depending on the viewing angle. Most tanzanite on the market is heat-treated to remove the brownish/burgundy tones and enhance the blue/violet.

Physical Characteristics

Tanzanite has a hardness of 6.5, which is relatively soft for a gemstone ring, making it susceptible to scratching. It has perfect cleavage in one direction, so it must be handled with care. Its main appeal is its vibrant, intense blue-violet color which can shift depending on the light source.

Historical Significance

Unlike most gems with ancient histories, tanzanite is a modern discovery (1967). It was heavily promoted by Tiffany & Co. in 1968, who declared it the 'most beautiful blue stone to be discovered in 2,000 years'. In 2002, it was added as a birthstone for December, the first addition to the list since 1912.