Tanzanite is the violet to blue variety of the mineral Zoisite. The gem is relatively new to the market since its discovery only took place in 1967. Mererani Hills in the Manyara Region of northern Tanzania in 1967, near the city of Arusha and Kilimanjaro. The only known Tanzanite mines are in Tanzania, the country which gave the gem its name. Even though the gemstone is new, it has gained immense popularity, just a few years after its discovery.
Primary shades of tanzanite are blue and bluish purple. Purple is a modified spectrum of tone that is halfway between red and blue. Tanzanite is a trichroic gem, which means that the light that enters the stone is divided into 3 sections, each with a part of the visible spectrum.
Tanzanites are generally heat treated to improve their clarity and color. By nature, tanzanite forms as a crystal with a brownish blue color. After the gemstone is mildly heated, the brown color disappears, purple and violet colors are highlighted. This heating process may be carried out by nature or by the hands of men. Tanzanites excavated from thermal sources are naturally heated by metamorphic heat, and some are heated in an oven after they are unearthed to mimic this natural process. It should be taken into account that heat treatment is not a guarantee that the gemstone will gain a deeper color. This has been proved again and again that gemstones with light colors do not gain anything from the heat treatment process. Compared to other gemstones, tanzanite only goes through a very mild heat treatment process. They are heated at 500 to 600°C degrees for a time period of less than an hour.
Tanzanite has a hardness rating of 6 to 7 on the Mohs scale, which makes it a somewhat brittle gem. While it is not the most durable gem, it is commonly used in rings, necklaces, bracelets, and earrings. The wearer should be extra careful and take precautions so that it does not get scratched or damaged.
While there is no globally accepted Tanzanite grading system, they may be classified according to their external and internal features, especially their color.