Tanzanite is a magnificent gemstone that's said to be a thousand times rarer than diamond. A variety of the mineral zoisite, it can only be found in a tiny area at the foot of Mount Kilimanjaro in Tanzania. Sadly reserves are dwindling fast and it's estimated that within thirty years the stone will be completely mined out. The finest gem grades of tanzanite command eye-watering prices per carat and they're often set with diamonds.
This rough piece of tanzanite has a slightly vitreous lustre which is best seen as it's moved around in the light but sadly we have not been able to capture this particularly well in our photo.
Renowned for its sapphire-blue colour which in part is the result of heat treatment, tanzanite is predominantly used for jewellery although rough pieces are always popular with mineral collectors and those who use the stone in alternative therapies such as crystal healing.
Weight (grams): 20.1
Size (cms): 3.8 x 2.7 x 1.5