December Birthstone

Birthstone December Tanzanite


A recently discovered gem born in the foothills of Mount Kilimanjaro.

Named by Tiffany & Co. after Tanzania, the country in which it was discovered by a Masai cattle herder in 1967, tanzanite has taken the world by storm and
continues to enjoy its growing popularity. Tanzanite is found commercially in only one place on Earth, making it many times rarer than diamonds.

Tanzanite is the blue to bluish purple variety of the mineral zoisite. The most prized is a pure blue color, similar to fine sapphire, or an intense violet-blue.
Viewing at different angles, tanzanite’s hue may appear violet. In some exceptional tanzanites, the color is predominately an intense violetish blue with red flashes of pleochroic color coming from within the stone.

Gem-quality tanzanite typically has no eye-visible inclusions. Any inclusions that might pose durability problems—such as fractures—lower tanzanite value
greatly. In rare cases, parallel needle-like inclusions may give a stone a cat’s-eye effect.

The only known source in the world is the Merelani Hills near Mount Kilimanjaro in northern Tanzania.

The vast majority of tanzanite is heat treated to transform brownish zoisite into violet or blue tanzanite. The result is permanent. Heat treating brown zoisite
converts the brown color to blue or violet hues depending on the orientation of the crystal. Rarely, fracture filling and color coating on the pavilion of a stone gives a desirable but temporary result.

Major Source


Mohs Hardness
6 to 7

Fair to Poor

Blue to violet to bluish purple


Care and Cleaning
Warm, soapy water is always safe. Ultrasonic and steam cleaners are
never recommended for tanzanite.

Source: The Passion of Colored Gemstones by G.I.A.