Tanzanite
Tanzanite is one of the newest of the gemstones. Discovered in 1967 and made popular by Tiffany, it would have been unknown to the old pirates. Today tanzanite sales in the US are thought to have an annual value of some $500 million.
What Is Tanzanite?
Natural tanzanite is a rare blue to purple form of zoisite. It's named after Tanzania where it was discovered in the north of the country. There's a story that the stone was discovered when lightning hit an outcrop of rock and heated it up to reveal its colour.
Whether or not that's true, most of the gem quality tanzanite you can buy on the market has been professionally heat treated to enhance its colour. Colour is a very important factor in valuing tanzanite and the highest quality stones are graded AAA for a deep, saturated tone.
Popular uses for tanzanite include rings (especially when set in white gold), pendants and stud earrings. It's one of the official birthstones of December and often forms a gift on the birth of a child, especially the first.