Tanzanite, with its blue-purple color, is found in just one place in the world, in the East African state of Tanzania. Tanzanite debuted in 1967. The Masai herders who drive cattle in the area noticed the beautiful blue color and picked the crystals up, becoming the first tanzanite collectors. It is the result of millions of years of geological "miracles." Because it was deposited at a very high elevation, it took a long time to be discovered by Masai shepherds who noticed the crystals sparkling in the sun. Tanzanites have a unique, trichroic effect, meaning that there are three colors (blue, purple and bronze) visible when the stone is looked at from different angles.
Today's tanzanite continues to be mined in the same place as it was discovered. Most crystals that are located are small, but occasionally a larger crystal is found. About 90% of tanzanite merchants are members of the International Colored Gemstone Association ICA, and bound by the high ethical standards of that organization.
Tanzanite is the blue iteration of the gemstone zoisite. On the Moh's hardness scale it is 6.5 to 7, making it not a very hard stone and one that should not be worn every day and with special care. It should never be cleaned in an ultrasonic bath, or put into contact with acids and should be stored where it will not rub up against any other jewelry, or itself. Most raw crystals are somewhat spoiled by a brownish-yellow component, but, fortunately, in the hands of a professional gemstone cutter, that part of the stone heated, so that the color will turn a velvety blue. This heating treatment is accepted in the industry and tanzanites are almost always enhanced in this way. Legend has it that the positive affect of treating tanzanites with heat was first discovered accidentally when brown zoisite crystals "appeared" after a fire set by lightning and spread through the grass-covered Merelani hills northeast of Arusha.