Tanzanite History

Tanzanite was first discovered in 1967 in Tanzania, East Africa. As one of the newest and most exotically colored gemstones, Tanzanite is part of the Zoisite mineral species and is only found in East Africa. It is named after the East African state of Tanzania, the only place in the world where it has been found. On its discovery in 1967, it was enthusiastically celebrated by the specialists as the 'gemstone of the 20th century'. The world's only known source of tanzanite is situated in the Simanjiro district of Tanzania, In the shadow of Mt. Kilimanjaro.

 

The Tanzanian government demarcated the tanzanite mining area into four blocks: A, B, C and D, measuring approximately 5km by 2km in total.

Color - Tanzanite is uniquely Trichroic, which means that in its rough form, it radiates three different colors from each of its axes: blue, violet and burgundy. Once cut and polished, tanzanite ranges from electric violets and pale blues to deep royals and rich indigos.

Tanzanite was rated fourth most popular colored gemstone in the US in 2002 and in 2003, the American Gem Trade Association named tanzanite a December birthstone, adding to a list previously unchanged since 1912.
 

Block D Tanzanite: is a term commonly used in marketing Tanzanite. Block D simply refers to the area from which material is mined. As mentioned earlier the Tanzanite mining area has been divided into 4 blocks by the Tanzanian government - Blocks A to D. Traditionally, larger quantities of the best material was found in block D so the term became synonymous with the top grade. However, it has become a marketing ploy and is a term misused as it implies that only block D produces the AAA grade. This is not the case - AAA comes from all blocks, block D has traditionally just produced more of it than the others. It is best to ignore the term as it is simply a marketing ploy and it is largely misused. It is better to use more scientific and official grades like the GIA system than to rely on subjective trade terms.

Choosing a Tanzanite
The most valuable Tanzanite's have an intense, vivid blue color in natural light. The best Tanzanite's hold the brightness of their color under all different types of lighting but due to the Trichroic nature of Tanzanite it can appear purple blue or bluish purple. In general, a more pastel blue would be less preferred than a vivid blue.