Tanzanite costs between $50 and $650 per carat as of 2015. Factors determining the cost include the quality of the stone and its relative size. The quality of the final cut also affects its value.
Tanzanite is 1,000 times rarer than diamond. The only known source of the gemstone is in Tanzania. It has a multicolored appearance and no industrial use. Geologists estimate depletion of the supplies of tanzanite by 2040. The chances of finding other supplies of tanzanite on earth are unlikely. However, the stone is less valuable than diamonds, and sellers undervalue tanzanite in terms of its rarity on Earth.