Gem Profile- Cat's Eye

by Judy Ellis

Cat's Eye

I think we are all familiar with cats. Cats are creatures that you either love, or hate. I have one cat in particular that will sit and stare at you, and I mean STARE at you, which is really creepy at night when you're sleeping. He is a solid gray cat with pumpkin orange eyes almost the same color as Tiger Eye, and when it's bright in the room, his pupil is just a tiny slit of black on a sea of orange. It's this effect that gave us the term "Cat's eye" in the gemstone world.

Chatoyancy is used to describe this phenomenon in gems and is the literal translation of "oeil de chat" which is cat's eye in French.

Chatoyancy (she-toy-en-see) not only describes the cat's eye effect in a stone, but is also used to describe the shifting luster in stones like tiger eye, pietersite and dumortierite as well.

What is Cat's Eye?

The cat's eye effect, or chatoyancy, develops differently depending on the gemstone. In a tiger's eye stone, the effect is created when crocodilite (asbestos) is replaced by silicon.

Tiger's eye colors include the familiar honey-brown, blue, green, and even red.

Other fibrous types of cat's eye include beryl, dumortierite, pietersite, corundum, and quartz.

To display the cat's eye effect optimally, chatoyant stones are nearly always cut en-cabochon or into smooth beads.

The smallest stones typically exhibit the sharpest effect.

About Cat's Eye

Cymophane, or oriental cat's eye, is a type of chrysoberyl and the most precious of the cat's eye stones.

It is a very hard stone, rating $8.5$ on the Mohs scale.In cymophane, the cat's eye effect is caused by thin tubes or voids within the crystal structure.If the inclusions, called silk, are rutile or asbestos, they form slightly differently in the chrysoberyl.

This difference creates a star or asterism effect instead of a single line.Ceylon sapphires, black star diopside, and Star of India rubies are the most familiar and most expensive stones that exhibit this type of chatoyancy.Natural cat's eye stones are found in various areas worldwide, including Brazil, Australia, Sri Lanka (Ceylon), and Russia.

Wrapped Amethyst Cat's eye in silver filled wire with two accent CZ stones.

One lavender colored and one amethyst color. Piece created and photo provided courtesy of Joan Ellen Madouse.

Now, what about the fun colors of cat's eye that we see? The cat's eye effect in these cabochons and beads is created by the same fibers that carry high-speed communications and create the really cool light that is used in Holiday decorations.

Yes, we're talking about fiber optics! To create the cat's eye cabochons, fiber optic threads are tightly bundled and embedded into glass.

This slab can then be cut into beads and cabochons of really any size or color.

Ring made with a blue glass Cat's Eye and argentium silver.

Ring created and photo provided courtesy of Adrien De Ruyck.

White Cat's Eye in antique copper wire with matching chain.

Piece created and photo provided courtesy of Joan Ellen Madouse.

So, from metamorphic transformations of tiger eye, to rutile inclusions and fiber optics, Cat's eye is a beautiful and intriguing stone that can mesmerize and captivate the imagination of jewelers worldwide.

Resources & Recommended Reading

About Cat's Eye on www.britannica.com
History and background about Cat's Eye on gemologyproject.com

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