In fact, only top-grade and A-grade Tanzanian blue has all the above characteristics. Grade B Tanzanian blue is dark purple, with little change in color, while Grade C Tanzanian blue is lavender, but the color is different from different angles. But all grades of Tanzanian blue have the same crystal, purity and refractive index. Moreover, as a finished product, even if it has color characteristics, if it fails to meet the requirements in terms of materials, cutting and polishing, it is impossible to have a corresponding grade. In the past, China's domestic jewelry industry called it "Tanzanite", mainly focusing on its difference from sapphire. Now it is renamed Tanzanite Blue, which emphasizes the similarities between Tanzanite and Sapphire.

So far, Arusha, Tanzania is the only producing area of Tanzanian blue. Tanzania's Minister of Mines said that this is a gift from God to the Tanzanian people. 1997, an individual businessman from China spent $60,000 in Tanzania's capital to buy a top-class Tanzanian blue, setting a price record at that time. Tanzanian blue sells well in the American market. With US President Bill Clinton, his wife and daughter visiting Arusha, the birthplace of Tanzanian blue, in 2000 and 1998 respectively, the price of Tanzanian blue in the US market has risen to almost the same as that of ruby.

Compared with three years ago, the price of Tanzanian blue in Tanzania has also tripled. The market price of top-grade and A-grade Tanzanian blue is above $300 per carat, B-grade Tanzanian blue is around $ 150, and C-grade Tanzanian blue is generally in the tens to $ 100. The price of special and exquisite varieties is not subject to this restriction. We can see ten thousand yuan of Tanzanian blue in the local gold shop.

Although Tanzania has such valuable resources as Tanzania Blue, it has not benefited from it. This is mainly because:

1. The mining management of Tansang Blue is chaotic, and the local people dig and dig indiscriminately, which has greatly damaged the deposit.

2. Only British and Indian jewelers have mastered the best processing technology of Tanzanian blue. They have advanced testing equipment and processing equipment, and also send many raw materials abroad for processing. The quality of Tanzanian blue processed by local businessmen can not meet the corresponding requirements, and there is no export capacity, so they have to sell it at a low price on the spot.

3. Tanzania does not have a mature gem market, and domestic sales and exports are limited by market conditions. Local jewelers in Tanzania go to Cairo or Las Vegas International Gem Expo to sell their gems (including Tanzanian blue) every year. In addition, the government lacks effective control over gem trading. A large amount of Tanzanian blue was smuggled out of the country.

The Tanzanian government has realized the above problems. They gradually took measures to protect the mining area and control illegal transactions. However, due to the lack of capital investment, it is impossible to establish a perfect domestic production and sales mechanism, and it is still impossible to use precious resources to achieve due benefits.

There are many imitations of tanzanite, but the most famous one is synthetic forsterite, which is made by Russians. Some merchants once called it "synthetic tanzanite", and forsterite synthesized in the laboratory usually has similar crystal structure and chemical composition with olivine. Chemical analysis shows that there are elements such as iron, vanadium and cobalt, which can make it appear blue-purple appearance.