Since tanzanite is a highly pleochroic gem, the color may be manipulated by cutting the crystal on one of two axes. Bluer stones are cut on the shorter axis and generally do not provide as high of a yield. While the pure blue shades command a slight premium, the strong violet hues are so popular that few stones are cut along the axis that reduces the purple tones. Rich color saturation is most prized, especially in smaller sizes. Large sizes are available when production is strong, but availability fluctuates with any change in conditions at the mine causing notable shortages in recent years due to flooding. In order to care for you gemstone, the best way to clean tanzanite is with warm soapy water and a soft cloth.
Brought to the attention of Henry B. Platt, then vice president of Tiffany & Co. in New York, tanzanite was named after its country of origin, Tanzania. Having one of the most famous jewelry companies in the world recognize tanzanite's potential was definitely serendipitous. But, as the supply was not stable, the marketing and promotion of tanzanite eventually came to a halt, causing tanzanite to fall back into obscurity.
The Tanzanian government, recognizing the potential for tanzanite, intervened in 1971 and made an effort to exploit this national resource. The mining and control of tanzanite was subsequently turned over to the State Mining Corporation around 1976. During this period, the mining and production of tanzanite fell off dramatically causing tanzanite to lose what little market share it had gained.
By the early 1980s, conditions had not improved, so production could be described as irregular at best. Toward the latter part of the '80s, thousands of illegal miners had flooded into Merelani Hills in Northern Tanzania and started exploiting the resources that were present.
It wasn't until 1991 that the Tanzanian government regained control of this area and started issuing licenses to mine. Most of the licenses went directly to native Tanzanians. Soon a temporarily sufficient tanzanite supply came to the market, allowing for tanzanite's tremendous growth.