A fairly common gemstone, which is not too well known because it so often looks like something else. It has the nickname "water sapphire" because it is usually bright blue, but unlike sapphire will appear lavender or gray when viewed from a different angle. (Usually the gems are cut so the brightest color is seen most easily.) Because of this pleochroic property, it is hard to cut and facet.

Gem-quality iolite is usually from Sri Lanka or Madagascar, and the stones are found in alluvial deposits. These water-worn stones are rarely very large, not more than one carat.