The Passion of
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.
Natural zoisite is usually brownish green or khaki,
however rarely it will naturally come out of the