Iolite is the gem form of cordierite, famous for trichroism so strong the Vikings reputedly used it as a polarizing sun compass: violet-blue, straw and near-colorless from different angles of one crystal. India, Sri Lanka and Madagascar are key sources; hardness 7–7.5.Our iolites are natural and untreated, certified by the GEMIC Institute laboratory, filmed to show their color play. Each is one of a kind; tracked delivery worldwide with 30-day returns.