Iolite (cordierite), is usually a purplish blue when cut properly, with a softness to the color that can be quite attractive. The best color is a lovely 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. Depending on the viewing angle, iolite will display violet blue, yellow gray or a light blue. Its hardness of 7-7.5 makes it a suitable jewelry stone.