Iolite Precious StonesHardness : 7.0 - 7.5 Appearance : Has stong pleochroism, meaning the gemstone changes colors depending which angle it is viewed from. Cordierite displays colors ranging from deep blue, to violet and light blue and grayish blue. It can be confused with tanzanite (zoisite) which is also strongly pleochroic. Enhancements : Iolite is not enhanced