This gemstone is called the gemstone of the Vikings, Iolite is also very often mistaken for Tanzanite. It derives it's name from the Greek work 'ios' which means violet.
This gemstone is bluish violet in color, Iolite with prominent blue color tones resembles blue sapphire and in lighter blue violet shades represents the more expensive, tanzanite.
The Iolite gemstone posesses a very important feature that is called pleochroism. This property posessed by a few other gemstones too, causes the gemstone to show different colors when viewed from different angles and sides. When viewed from one side the Iolite gemstone will show a gorgeous bluish violet color and when viewed from the other side, appears very pale colored and almost colorless.
Gemstone of the Vikings is related to the pleochroism feature of the iolite gemstone. It is believed that the Vikings used the Iolite gemstone to help them navigate on the high seas when very far away from the coastline. Looking through the gemstone at a certain angle, the Vikings could determine the exact position of the sun and never got lost when on the high seas.