Iolite

Named from the Greek ios, or violet, iolite has extreme pleochroism. Iolite has different colors in different directions in the crystal. A cube cut from iolite will look a violetish blue from one side, clear as water from the other and a golden yellow from the top.

Color
Iolite is usually a purplish blue but may range from gray to purple to a less saturated blue.

Origin
Iolite is mined in India, Sri Lanka, Mozambique, Zimbabwe, and Brazil.