Iolite

 Iolite is different colors in different directions in the crystal. A cube cut from iolite will look violet blue almost like sapphire from one side, clear as water from the other, and a honey yellow from the top. This property led some people to call Iolite "water sapphire" in the past, a name that is now rarely used.

The name Iolite comes from the Greek Ios, which means violet. Iolite is usually a purplish blue when cut properly, with a softness to the color that can be quite attractive.

Iolite is readily available and surprisingly affordable. The better and richer the blue, the better. It is mined in India, Sri Lanka, Mozambique, Zimbabwe, and Brazil.