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The Gemstone Kyanite

Kyanite is more of a collector gem then a mainstream gem, and has not been extensively mined for gem use. Gem quality Kyanite has traditionally come from Brazil, Cambodia, and Burma, but these stones are generally not colored consistently . They usually have a grayish tone, and are not fully transparent, thus limiting their use as a gemstones. However, recent finds in Nepal of high quality Kyanite have been delivering gemstones of exceptional blue color and transparency, rivaling Sapphire.

Color

Blue

Hardness

4.5 - 7

Chemical Formula

Al₂SiO₅

Mineral Class

Kyanite

Additional Properties

Crystal System
Triclinic

Refractive Index
1.71 - 1.73

Double Refraction
-0.015

Transparency
Transparent to translucent

SG
3.5 - 3.7

Luster
Vitreous

Cleavage 1,1;2,1

All About

The blue color of Kyanite is usually inconsistent in crystals, with lighter and darker color zones and streaks often present. This can make cutting a crystal into a gem a challenge as color consistency in a gem is more desirable. Kyanite can also form in other colors such as colorless, white, green, yellow, and orange, but these other colors are uncommon, and generally only the blue color is used as a gemstone. Kyanite gemstones rarely display asterism in cabochons.

Kyanite is the most anisotropic of all gemstones, meaning its hardness differs on its horizontal and vertical sides. It is fairly soft when cut parallel to the long axis of the crystal, with a hardness of only 4.5 to 5.5. On the shorter side of the crystal the hardness is 6 to 7. This unique hardness property plays a role when cutting a crystal. Care must also be exercised not to scratch Kyanite gems as they are fairly soft for a gemstone (specifically on their horizontal axis).

Uses

Kyanite is used as a minor blue gemstone. It is can be cut into various gemstone facets and cabochons. In jewelry, its use is limited mostly to earrings and pendants.

Other Names

Cyanite

Treatments & Enhancements

Kyanite gemstones are not heated or enhanced.

Kyanite Sources

Traditional Kyanite sources of gem crystals include Brazil, Cambodia, Burma (Myanmar), Switzerland, Russia, Kenya, and the U.S. (North Carolina, Connecticut, and Maine). A relatively recent discovery of Kyanite in Nepal in 1995 has produced gem crystals of Kyanite of exceptional color and transparency.

Similar Gemstones

Sapphire can appear similar to Kyanite, but can be distinguished by its greater hardness. Iolite is visibly pleochroic, and Tanzanite is usually lighter in color and has a more purplish hue.