Iolite

About Iolite

Also called water sapphire and Vikings Compass. Viking navigators used thin slices of iolite as polarizing filters to determine the position of the sun on cloudy days - the first known use of a polarizing lens. It is strongly trichroic - showing blue, violet, and yellow-gray from different angles. The name comes from Greek ion (violet). It is found in Sri Lanka, India, and Madagascar. It is affordable and available in good sizes. The best color is a rich sapphire-like blue. It is relatively hard and suitable for all jewelry types. It is a cordierite mineral.