Tanzanite is a gem form of zoisite, found only in the Arusha region of Tanzania. Mining is very deep, as gemstones easily go for $250 - $1000+ per carat. Crystals are also produced, of varying quality given largely that anything with a gemmy area within it gets cut. Also most are dinged, so getting pristine specimens is very difficult. Most pieces are heat treated, which mimics the natural geology that gives the crystals that amazing blue-purple color. 

This crystal has a natural steely blue color with a yellow accent in its base. It has a little scraping on it back edge. It weighs 8.65 carats.