Tanzanites are actually 1000 times rarer than diamonds. Gem quality Tanzanite originates from one place on Earth- The Merelani area in Tanzania.Its magnificent colour display is the result of Pleochroism which is a gems ability to display several colours. Discovered in 1967 by a Masai tribesman this beautiful gem was marketed heavily by Tiffany and Co as reletavily affordable alternitive to its Sapphire counterpart. By 1969 the gem was identified to be a member of the Zoisite family consisting mainly of silica, calcium and aluminium. Tanzanites are highly prized for there vivid colour which,95% of the time, is derived by heating the gem stone to approximately 1100°F to 1200°F. When Tanzanite is mined it is typically a brownish colour. Heating the stone turns this to a uniform blue. Tanzanites rate 6 to 7 on the Mohs scale of hardness. Prices of this gem have fluctuated widely over the years due to instability in the region with supply with the deeper and more vivid colours generally commanding a higher price per carat than that of a weaker lighter colour. The main cutting centre for Tanzanite is in Jaipur India. For every tonne of earth mined only 12 grams of gem quality material is found.CM Weldon has a beautiful example in store.

Tanzanite Imitations:

Synthetic Forsterite is Pleochroic gem that sells for a tenth of what gem quality Tanzanite sells for.

Glass has sold for Tanzanite as well as YAG (Yttrium Aluminum Garnet) and Coranite which is a trade name for synthetic bluish corundum

Some Tanzanite Facts: 

Gem Species: Zoisite

Hardness Mohs Scale :6.5-7

Crystal System: Orthorhombic

Fracture: Uneven to Conchoidal

Specific Gravity: 3.10-3.38

Refractive Index: 1.69-1.70