Lot Of 4 Cushion Cut Tanzanite Gemstone 2.45 Carat Total Weight Tanzanite is a rare and precious gemstone, which has been coined a 'geographical phenomenon' because of the unusual formation of the stone. The only known source this stone can be found in is a thin strip of land at the foothills of Mount Kilimanjaro located in Northern Tanzania, in East Africa. Due to the stupendous rarity, experts suggest the chances of the stone occurring somewhere is 'one in a million'. This gives the stone its own unique position in the world of gemstones and diamonds. But, instead of tanzanite joining the gemstone family, its rarity branches it off into its own category. With this in the mind, the stone is a must have for any collector, jewelry store owner, and jewelry wearers alike.