Alongside andalusite and sillimanite, kyanite is one of the three aluminosilicates that may occasionally be encountered as faceted or cabochon-cut gemstones. The mineral also has many important industrial uses, including as an ingredient within ceramic items that are likely to be exposed to high temperatures.

Kyanite’s most distinctive property is its differential hardness, which causes it to be very soft (4.5-5.0) in one direction and acceptably hard (6.5-7.0) perpendicular to this. When combined with the mineral’s vulnerable directional cleavage and typically uneven color distribution, this direction of extreme softness has somewhat limited kyanite’s popularity as a gemstone.

Named after the Greek word for “deep blue”, kyanite is almost always associated with the sapphire-like blue hues of the most prized Nepalese material and, to a lesser extent, light greens. However, Tanzania has recently started producing gem-quality orange crystals, which are colored by the presence of trace manganese impurities.