Its deep, vivid blue with a hint of violet and the exclusivity of its origin make tanzanite one of the world’s most wanted gems. This precious variety of the mineral zoisite is found on only one site in Tanzania.
Formula: Ca2Al3(SiO4)(Si2O7)(O, OH)
Hardness: 6.5 – 7
Density: 3.20 – 3.50 g/cm3
Refractive Index: 1.690 – 1.707 DR: 0.008 – 0.009
Color: Blue, purple, purple-blue
Countries of Origin: Tanzania
Birthstone: December