The name “Tanzanite” was proposed by the jewelry company Tiffany & Co, New York, The stone was called in the honor of Tanzania, the country, where the single tanzanite deposit in the world is located. It’s just a trade name. The tanzanite is a variety of the zoisite (called after the Austrian collector S. Zois, who sent the mineral for a study).
This gemstone is about 1000 times rarer than the diamond. The tanzanite reserves are preliminary estimated to suffice for about 20 -45 years of the mining.
Stones of a good quality have ultramarine-blue and sapphire-blue colorsandacquireamethystine-violet shades under an electric light.
The distinctive feature of the tanzanite is a pleochroism (the stone changes its color shades when observed at different angles) appearing blue, red-violet, green and brown colors. There are tanzinites with the “cat’s eye” effect, which can be seen on a surface of a cabochon cut stone as a band of light. This band moves across the stone when it is rotatednear the light source.
Today almost all tanzanites are heat treated. After a small heat treatment of deeply colored crystals the beautiful sapphire-blue color emerges. During heating pink and yellow-green zoisites change their colors to light-blue. Green-blue tanzanites with brown and yellow color shades appear deeper blue color and violetish pleochroism. Up to 90% of tanzanites come to the market after the heat treatment.
The tanzanite was discovered in 1967, but it was finally recognized and acknowledged by the Tanzanian Government only in 1984.The total mining area in which the tanzanite is found is a mere 16 km².
Besides small crystals relatively big tanzanite crystals, which weight between 10 and 50 carat, can be found. The biggest, more than 3 kg (16839 carat), tanzanite crystal was found in the deposit of the Mererani Hills.
The jewelry company Tiffany & Co, USA, which has marketed tanzanite as a brand new gemstone, created a unique necklace with five cut tanzanites for the cinema star Elizabeth Taylor. The world’s most famous faceted tanzanite is 242 carat weight. It is set in the tiara “Queen of Kilimanjaro” together with 803 tsavorites (rare green garnets) of 32 carat weight and 913 diamonds of 14 carat weight. One of the world’s biggest faceted tanzanites of 220 carat belongs to a private collector. The pure blue faceted 122.7 carat stone and the 18.2 carat cabochon with the “cat’s eye” affect are located in the Smithsonian Institution in Washington, USA.
There is an opinion that the tanzanite was used as a stage property for filming “Titanic”. It was featuring in the film as the famous blue diamond “Heart of the Ocean”.
In 2003 the American Gem Trade Association named the tanzanite as a December birthstone, adding to a list previously unchanged since 1912.
Today tanzanite jewelry can be easily found on the European and the United States gemstone markets. In Russia this stone is still comparatively new and rare.
It is remarkable that for most of the last 10 years the tanzanite was among the top four selling gemstones the USA.