The name iolite comes from the Greek "ios", which means violet. The Vikings probably mined iolite from deposits in Norway and Greenland. Viking sailors used iolite as a polarizing filter to find the sun on cloudy days for safe offshore navigation. Iolite is usually a purplish blue when cut properly, with a softness to the color that is quite attractive. The favorite color is that pretty, violet blue that is unlike other gemstones. Pleochroism is very pronounced in iolite and is seen as three different color shades in the same stone. In viewing an iolite stone, the colors violet blue, yellow gray and a light blue can be seen; all a result of pleochroism.