Iolite is a relatively hard gemstone but also brittle. It can break very easily which makes cutting difficult.
The colour of the finest material can be mistaken for blue sapphire or tanzanite. However, iolite is rarely heat-treated.
The names 'water sapphire' and 'dichroite' have both been used in the past. Dichroite, which means 'two coloured rock', refers to iolite's strong pleochroism.
It has also been called the 'Viking Compass'. The Vikings are said to have used iolite as a polarizing filter to navigate the seas. By looking through a thin slice of iolite, they could determine the precise position of the sun on an overcast day.
Today when used for crystal healing iolite is said to enhance navigational skills. It's believed to make determining your precise location easier and can help with directions and distances.