Kyanite, Al2SiO5, has a triclinic crystal system with a refractive index of 1.712 - 1.734. The hardness of the gem on the mohs scale is 4.5 to 5 parallel to crystal length and 7 to 7.5 perpendicular to length. This relatively low hardness makes the gemstone best suited for earrings, pendants or brooches. If kyanite is to be used in a ring, the wearer must use caution to avoid damaging the stone. Kyanite gems of fine color and transparency are rare. Fine kyanite rivals the look of the best blue sapphires. More Information on Kyanite is Here! We have the following kyanite gemstones in stock: