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Antwerpen 2018



What is tanzanite? Tanzanite is a rare and valuable stone that relates to the silicate group. The official title of the mineral is zoisite. This unique stone first saw the light of day only recently but has already managed to win the hearts of jewelers and become one of the most expensive minerals. While other expensive gemstones sapphire, emerald, and others were remembered even before our era, tanzanite is a “contemporary”. It was found in 1967 and got its name thanks to the jewelry company Tiffany Co., which proposed to name the stone after the place of its extraction.

This amazing and unsurpassed gem hides a lot of mysteries, and today we will try to reveal them all for you. In this article, you will learn in more detail about what tanzanite is, where it is mined, its fascinating history of discovery, cost, properties, meaning, and much more. If you are interested in this stone, then you can browse our catalog and look at lots for your personal parameters. Even if you do not find what you were looking for, our staff will be happy to help you in your search and find the tanzanite of your dreams!

Tanzanite properties

The chemical formula of the gem is Ca2Al3 (SiO4) (Si2O7) O (OH). In fact, tanzanite is a silicate of aluminum and calcium. The most distinctive feature of tanzanite is that the stone has a pleochroism effect and changes color depending on the light and even the viewing angle. These can be shades from sapphire blue and tan to red and purple. Other tanzanite properties include:

Tanzanite propertyValue
Optical characterOptically anisotropic, 2 +
Refractive indexng = 1.697-1.725, nm = 1.688-1.700, np = 1.685-1.705
PleochroismStrong trichroism: purple, blue, brown, or yellow
Dispersion0.030 (BG), 0.011 (CF)
Density, g/cm33.35
CleavagePerfect (in one direction)
Hardness (Mohs scale)6.5-7
InclusionsGraphite inclusions are characteristic

Tanzanite varies in color from sapphire blue to deep purple. Existing examples of a yellowish-brownish color are not popular in the jewelry field. The luster of this gem is glassy, which allows you to enjoy its beauty without any blurs and oiliness. We also want to highlight the geological features of this stone, which are so unique that the likelihood of discovering tanzanite deposits in other countries is extremely small. The only tanzanite deposit in the world is gneisses carrying a system of veins with voids and cracks with crystals growing on their walls. They are widespread in placers near parent rocks in the form of fragments, elongated or irregular grains.

  • The real natural color of the bulk of tanzanite extracted from the earth is gray and even brownish. However, when treated, the mineral acquires beautiful colors, ranging from light lilac to purple. The ideal color scheme, the so-called royal, is considered to be a pure blue stone.
  • It is possible to find Tanzanite cat’s eye. The color is due to impurities: blue impurities of vanadium, greenish-blue impurities of vanadium, and chromium.
  • Crystals can sometimes have shading along with the form.
  • Due to the natural creation in the bowels of the Earth, unheated tanzanites have a magnificent color, the beauty of which cannot be compared with the color that a person creates.

Tanzanite cost

As mentioned earlier, tanzanite is a very costly and rare stone. Therefore, its cost has always been high, although it could not exceed the price of sapphires. In recent years, the value for tanzanite has been about $300-400 per 3 carats of a cut stone. And of course, natural blue and violet-blue stones are more expensive than heat-treated ones, however, since “unsuitable” tanzanites make up almost 95% of all mined stones.

Tanzanites are widely used in jewelry for making expensive items. It is also beneficial to use this stone as an object for investments. But for this, only large gems from 10 carats with the highest purity or rare collectible samples of high quality are suitable. The price of large-sized tanzanite (over 2 carats) can go up to $2,000 or more per carat.

Carat weightCost of low to medium quality stones, $Cost of medium and high-quality stones, $
Up to 0.2910-1540-110
10 and more300-500420-650-1200

The highest price per carat is for stones with a color that is 80% saturated blue. Also, when it comes to a stone with decent quality, its price can sometimes reach the value equal to a good diamond. This is due, again, to the rarity of tanzanite, as well as the quality of the cut. Only very experienced jewelers undertake its cutting the mineral is quite fragile and difficult to process.

History of the discovery of tanzanite

History of the discovery of tanzanite

Tanzanite was found in the summer of 1967 by the Portuguese prospector Manuel вe Souza, who sent an expedition to Tanzania in search of rubies. As guides and assistants, he was accompanied by a detachment of local residents Masai hunters (the Masai are the largest tribe of indigenous people inhabiting the territory of Tanzania).

Several weeks passed in fruitless search, when at the foot of Kilimanjaro, in the province of Arusha on the Merelani plateau, but the campaign was crowned with success. That day they first encountered the “What is tanzanite?”. Large, transparent, violet-purple crystals, which were originally mistaken for sapphires, were found in cracks in the rocks heavily altered due to the influence of high temperatures and pressures. But the stone was too soft for a sapphire.

The examination showed that the new stone is a variety of fairly widespread mineral zoisite, and the attractive blue color is due to the admixture of chromium and vanadium ions. Zoisite has been known since 1805 and has not been used in jewelry. The tanzanite gem would have remained unknown if it had not caught the eye of the vice president of the jewelry house Tiffany Henry Platt. He appreciated the tanzanite properties and its unique beauty.

The meaning of tanzanite has had a great influence on the development of jewelry. The following are considered striking examples in the history of the stone:

  • The Blue Book collection, released in 2015 by Tiffany Co., boasts a 23.03-carat dark blue tanzanite gold ring. Tanzanite rings, necklaces, and brooches from Chanel’s Les Talisman collection have taken it to the top of the Olympus of the jewelry world.
  • One of the brightest jewelers of our time, Ornella Iannuzzi, did not hesitate a second when choosing a stone for her new masterpiece: a tanzanite pendant weighing 45 carats. The stone was processed by hand for over 200 hours before being set in white gold with diamonds.

Meaning of tanzanite

Tanzanite is a birthstone for December, along with zircon, turquoise, and blue topaz. Tanzanite is also the gem for a 24th anniversary. Therefore, jewelry with tanzanite will be the best gift for 24 years of marriage. The fact is that this date divides the life of the spouses into “before” and “after”, and this mineral is the best suited for expressing the tender feelings of loving people.

Tanzanite deposits

Tanzanite deposits

The high cost of a unique stone was initially determined by the fact that there is only one deposit in the world where it is mined. It is located in Tanzania, near Mount Kilimanjaro. And in the next decade, according to experts’ forecasts, it may be exhausted. Until the 90s of the last century, tanzanite was mined mainly by private miners. In 1990, the Tanzanian government decided to streamline field development. The territory of the field was divided into four areas blocks A, B, C, and D with subsequent licensing of mining companies.

  • Blocks A and B, located in the rugged mountainous terrain, as well as Block D, where ore-bearing layers are overlain by thick layers of soil and waste rock, which significantly complicate mining, was intended for development by local mining companies.
  • The territory of Block C is the most convenient in terms of development, was intended for development by foreign mining companies, and is currently the main source of tanzanite.

Mining in Block C began in 1995 by Graphtan Ltd. (Great Britain), from 1999 to 2004, African Gem Resources Ltd. (South Africa) was involved in the development of the deposit. And from 2004 to the present, tanzanite has been mined by the Tanzanite One Group -Tanzania (today it controls 50 to 60% of the explored tanzanite reserves).

Tanzanite One’s tanzanite deposit is the largest operating in Tanzania. The main mining is carried out underground (the length of some mines reaches 400 m and a depth of about 300 m below the surface of the earth). In some areas, the tanzanite content in 1 ton of ore can reach 60 carats.

Interesting facts

  • The world’s largest faceted tanzanite weighs 242 carats and is housed in the Queen Kilimanjaro tiara owned by Apple Computers CEO Michael Scott.
  • Tanzanite’s meaning gained great popularity and fame due to the fact that Elizabeth Taylor had a special love for it and repeatedly appeared in jewelry with this stone.
  • According to one of the versions, tanzanite was the central stone in the famous “Heart of the Ocean” necklace with a heart-pendant used in the movie “Titanic”.
Tanzanite gemstone

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