Gem of the Vikings

When Leif Eriksson and the other renowned Viking explorers ventured far out into the Atlantic Ocean, away from any coastline that could help them conclude position, they had a secret gem weapon: iolite. The Viking mariners used thin pieces of iolite as the world's first polarizing sift. Looking through an iolite lens, they could decide the exact position of the sun, and navigate safely to the new world and back.

The property that made iolite so precious to the Vikings is tremendous pleochroism. Iolite has different colours in different directions in the crystal. A cube cut from iolite will look a violets blue almost like sapphire from one side, clear as water from the other, and a honey yellow from the top. This property led some people to call iolite "water sapphire" in the past, a name that is now superseded.

Pleochroism may have been helpful in direction-finding but it makes things difficult for a gem cutter. If iolite is not cut from exactly the right direction, no matter the shape of the rough, its colour will not show to its best benefit.

The name iolite comes from the Greek ios, which means violet. Iolite is usually a purplish blue when cut properly, with a gentleness to the colour that can be quite striking.

Iolite is readily available and surprisingly reasonably priced. The better and richer the blue, the better. It is mined in India, Sri Lanka, Mozambique, Zimbabwe, and Brazil. The Vikings almost certainly mined iolite from deposits in Norway and Greenland.

Iolite is comparatively hard but should be protected from blows. With its good-looking colour and reasonable price, it may become a jewellery staple in the future.