Tanzanite gemstone is a blue variety of Zoisite. Found exclusively in Tanzania, near the foothills of Kilimanjaro. Very few stones are actually found in the desired violetish blue colour. Most have far too much yellow and brown in them and must be heated before they can be used in jewellery. Some say that’s how all blue coloured tanzanites came to be. Through natural heat deep within the earth. However there’s a way to tell the difference. Stones that come originally blue from the ground are trichroic while the heated ones are dichroic. That doesn’t make them less beautiful or physically worse but as with other gemstones, untreated Tanzanites command premiums.
Tanzanite is relatively brittle, so it is better to use it in earrings and necklaces, rather than rings. This way there’s less chance of damaging it accidentally. The most desired hue of tanzanite is violetish blue, vivid tone without any grey or brown mask.