It is known as Zultanite or by Gems TV, Csarite. They tend to buy most of it up from the mine owner Murat. The quality coming from his mine is extremely good but beware of cheaper heavily included pieces and counterfeit as it has become quite desirable. I have various pieces ranging from 1.46ct to 3.52, but as stated before, colour change is rarely detectable under 2+ carats. Probably a potential investment stone, but buy as clean and large as you can afford.