Skip to content

Tanzanite: The Gemstone of the 20th Century – Blue Treasure of Africa




The Tanzanite gemstone is a zoisite mineral composed of calcium hydroxide silicate with aluminum, with a blue and purple color, was first discovered in the Mererani Hills of the Manyara Region with direction towards the north of Tanzania in the year 1967, near the city of Arusha and the Kilimanjaro. Currently used as a gem, it can be distinguished by its marked tricroism, represented by its sapphire blue, violet and burgundy color according to the orientation of the crystal.

This crystal can change its appearance depending on the lighting and the conditions in which it is, its blue color becomes more evident when exposed to fluorescent light and incandescent lights makes it to lookmore with violet tones. Raw, the tanzanite is usually a reddish brown color which is necessary to undergo a heat treatment at 600 ° C in the furnace so that the blue violet shade appears.

Tanzanite is a very rare gem. It is only found on the slopes of Mount Kilimanjaro and it was the company of Tiffany & Co. that gave it the name, inspired by Tanzania, the country where it was found. Due to its relatively low hardness, tanzanite is used to be assembled in necklaces and earrings.


  • It has a variety of blue and purple zoisite colors.
  • The tanzanite next to its blue violet can easily be compared with some beautiful sapphires.
  • It was found in 1967 in the Mererani Hills, located near the city of Arusha, northern Tanzania.
  • Next to the zircon and the beautiful turquoise stone it is native for the month of December.
  • When the tanzanite is carved it becomes a valued and popular gem forjewelry. It stands out for its tricroism that according to the orientation of the crystal, it appears with the shades of sapphire blue, violet or green.
  • It is a scarce gem, it is only found on the slopes of the Merelani in Tanzania, discovered in 1967. It has a metamorphic origin in all areas of regional metamorphism.
  • The name Tanzanite was given by the Tiffany & Co company in the marketing campaign aimed at placing the stone in the market and increasing its value.
  • The production of tanzanite delivers to Tanzania about 20 million US dollars per year, although the value of the carved jewelry amounts to 500 million dollars per year.
  • There is a unique tanzanite site in the world. There the mineral is accompanied by metamorphic slate, gneiss and quartzite. This mineral is only found in the hills of Merelani, Tanzania), its exclusivity is the main reason for the high price of this stone, which is also called by the name “the indigo diamond” because of its rarity.


Some of these found stones have a slight yellow-brown pigmentation, which can be removed with a thermal treatment at approximately 500 ° C., Has a hardness of 6.5 – 7 on the Mohs scale.The tanzanite is, of the three varieties that zoisite has, the most important. It is an aluminum and calcium silicate belonging to the group of the epidote.


When the stone is of good quality, a color of ultramarine blue to sapphire blue is observed. Under artificial light the color is an amethyst violet. The tricroismcolors, which can be appreciated with the naked eye, are: blue, purple red and yellow greenish brown.

The color is violet brown due to heating and vanadium, this makes it get that blue that is how it is sold. The brightness is vitreous. Despite their color, they are very transparent.


All these gems are heat treated to get that blue color that characterizes them. Tanzanite can be easily confused with iolite, which is also tricroric, amethyst, sapphire, and spinel; but it can be differentiated from all of them by its physical and optical properties.


Legend has it that the Masai discovered tanzanite after a fire caused by the fall of lightning or the lightning itself, and that some yellow-brown stones not very attractive (Zoisite) happened to have a precious blue-violet-purple color.

The tanzanite is a magical tricroism jewel, as the iolite with the andalusite, whose fundamentalcharacterization is that all and I say all those that are marketed have undergone a series of thermal works that gives them that color so characteristic of the jewel.

Unlike other gems, it is insensitive to acids; however we should not clean them with ultrasounds but with water, soap and a soft cloth.


As for the name of tanzanite, it was introduced by the jewelry company Tiffany’s New York, at first it had the name of “blue zoisite” but its name in English did not sound very good, since it seemed “blue suicide”, so Tiffany’s decided to give it a more commercial name in order to introduce it to the market, and chose the name of the country by calling it Tanzanite. Between 1967 and 1972 an approximate 2 million carats of the Tanzanite jewel was extracted from the mines, this was before the government was nationalized.

The largest tanzanite in the world has a weight of 737.81 carats. There is a very famous and beautifultanzanite specimen of about 242 carats called the “Queen of Kilimanjaro”, set in a tiara with 803 granatestsavoritas and 913 brilliants, this impressive piece is part of the private collection of Mickael Scott the first Apple executive.

In June 2003, the Tanzanian government banned the export of raw tanzanite to India (where the vast majority of gems are carved in Jaipur) to encourage local industry, in an attempt to stimulate the economy and reap benefits.

In April 2005 the company with the name of Tanzanite One Ltd, openly announced that it took control of the production of block C (the main deposit, divided into five blocks), with this the price of the raw material has been increasing, just like the company has been settling in the market. In August 2005, in Block C, they found the world’s largest tanzanite at the moment of 16,839 carats or 3.4 kg.