Tanzanite, which is the blue gemmy form of the mineral ziosite, is a fairly recent gem discovery, having been located in Tanzania, Central Africa by Tiffany & Company and named in honor country of origin. Today, Block D or top color Tanzanite is difficult to come by in large carat stones, as the deposit is pretty much mined out. As a result, much Tanzanite offered on the market is lab grown synthetic material and buyers must beware.