Iolite, also previously known as ‘water sapphire’, is the gemstone variety of the mineral cordierite. The name itself comes from the Greek word for violet, with the gemstone usually displaying a pale violet-blue color which often sees it used as a cheaper substitute for sapphire.

Iolite is quite readily available, being mined predominantly in Brazil, India, Sri Lanka, Burma, Mozambique, Zimbabwe and Tanzania. The gem is relatively hard, but is still softer than sapphire, which is the main reason that it is lower in cost, needing to be protected from hard blows.

In history Iolite held more than just an aesthetic purpose, with the Vikings using it as a navigation aid when exploring out at sea. Thanks to a unique property of the gem which is known as pleochroism, the Vikings were able to use thin strips of iolite as a polarizing filter to determine the exact position of the sun and hence find their own position and direction.

Pleochroism basically refers to the fact that iolite has different colors when the crystal is viewed in different directions. For example while the crystal usually exhibits a pale violet-blue color, it will appear almost crystal clear from another direction while then appearing honey yellow from another.

This property can make it fairly difficult to get a good cut of iolite, since the color can only be shown at its best if the direction of the cut is absolutely correct. When this is achieved however, the stone offers a beautiful effect with changing light angles, a desirable property in many of the jewelry designs in which the stone is used.