Beauty is in the (cat's)Eye of the Beholder

To be classified as a gemstone, a mineral must be beautiful, rare and durable. Likewise, a phenomenal gemstone must have some unique optical effects.

One such effect is commonly referred to as “cat’s eye”, although the technical term is chatoyancy.

 The term “Chatoyancy” is believed to be derived from the French ‘œil de chat – (Ue-Ye Dae Ch-aat) meaning “Cat’s Eye”

~Tiger's Eye gemstone showcasing a true "eye"

Chatoyancy shares some similarities with asterism; they both showcase light bands that seem to ‘move’ across the stone. They are also often cut as cabochons to bring out this feature.

However, there are multiple causes of this effect.

One is rutile needles, just like star stones, but only needles oriented in a single direction rather than in an intersecting pattern.

The other cause is a fibrous structure, such as with Tiger’s Eye and Hawk’s Eye gemstones. This makes the stones have a ‘silky’ appearance, which stems from how the crystals grow.

~ Strand of Tiger's Eye beads

Chatoyancy creates a line or stripe of light that seems to glide across the surface of the stone as it, or the observer, moves.

This effect is readily observed in man-made carbon fiber or optic glass pieces, and can also appear in natural wood.

While some woods can be treated to enhance this effect, it is a natural occurring phenomenon in many hardwoods from Asia. It is caused by stress when the trees are growing, which causes more compact and higher density areas in the wood grain.

~ Close-up images of the fibrous structure of Tiger's Eye; photos by Isabelle Corvin

Gemstones that are known for chatoyancy are the previously mention tiger’s eye and hawk’s eye, as well as chrysoberyl, rose quartz and feldspar, and rarely beryl, tourmaline, and others.

All gemstones that display cat’s eye effects have been said to ward off evil spells and protect against the ‘evil eye’ since ancient times.

Cat’s eye chrysoberyl is rare and stunning, usually sporting a very intense “eye”. Modern crystal practices say that cat’s eye chrysoberyl will enhance one’s night vision.

Since chrysoberyl wasn’t known to be a unique gemstone in ancient times, it was often lumped together with lore surrounding brown or golden stones, like with topaz.

~ Ring set with a cat-s eye chrysoberyl by Stanton Color

Tiger’s eye and Hawk’s eye gems share many traits, said to increase observation skills and be excellent protective talismans.

Some records from Egyptian history show that they would occasionally set tiger’s eye or hawk’s eye stones into the center of ‘eye’ motifs in carvings, statues and jewelry, obviously taking advantage of natural effect for some artistic flare.

The eye symbol was a revered and important motif for Egyptian lore throughout history.

Stories exist of Roman soldiers having tiger’s eye stones amulets, or setting the stone into armbands.

Given that it is a ‘bold’ looking stone, tiger’s eye is sometimes associated with traits like courage, strength and vitality. It is also said to help with confidence and promote good luck.

Like with all phenomenal gemstones, ‘cat’s eye’ or chatoyancy effects are stunning, and almost unbelievable.

If you are looking for a true statement piece, you might try a mysterious and daring gemstone with chatoyancy.

~ Blog by Isabelle Corvin, staff gemologist and merchandising manager