Kyanites

Kyanite is named after the Greek word for "blue". Its color indeed can make it a lovely gem with a near sapphire-like blue. Usually its color is blue but also can be colorless, white, gray, green or yellow. Color is often not consistent throughout the crystal, often showing white streaks in a medium blue. Luster is vitreous to almost pearly. Its variable hardness is a significant characteristic that has to be taken in consideration by the gem-cutter.