(from top) Cat’s eye alexandrite; Cat’s eye tourmaline; Cat’s eye chrysoberyl (image: Nan Yang gemological Institute)

WITH its narrow, bright band of light that cuts across its golden surface like the eye of a feline, the cat’s eye is a miracle of nature that has fascinated mankind since ancient times.

What is cat’s eye?
The term ‘cat’s eye’, when used by itself, refers specifically to cat’s eye chrysoberyl. It is the chatoyant variety of chrysoberyl that is highly prized among connoisseurs and collectors. When properly cut, the gem displays a sharp, well-defined line down its centre that resembles a cat’s eye, due to very fine fibrelike inclusions. This optical effect is referred to as chatoyancy. Since ancient times, the cat’s eye has been perceived as a talisman, due to its surreal cat’s eye-like quality, and its excellent hardness and durability.

Other gemstones can also exhibit chatoyancy and the cat’s eye effect. These include cat’s eye tourmaline, cat’s eye moonstone and cat’s eye quartz. However, fine quality cat’s eye chrysoberyl sets the standards amongst other cat’s eye varieties.

What are the best colours?
The best quality cat’s eye chrysoberyl has a milk and honey-like effect with superb translucence. Cat’s eye alexandrite is rarer and shows chatoyancy and colour change. Where do they come from? Major cat’s eye chrysoberyl sources include Russia, Brazil, Madagascar, Sri Lanka, Burma, India and Tanzania.

What about treatments and imitations?
Cat’s eye chrysoberyl may be treated to improve the colour. The most frequently seen imitations are cat’s eye glass. Synthetic cat’s eye alexandrite exists. Most frequently seen imitations are glass, plastic or assembled stones. If in doubt, consult a reputed gem testing laboratory.

Buying Cat's Eye
• Look at the eye. Is it sharp, well-centered and correctly oriented? The eye should open and close smoothly. When a penlight is shone directly overhead, a fine cat’s eye will open and close like a cat’s pupil.
• Look at the body colour. Does the stone have a good milk and honey-like effect? When a penlight is shone on a fine cat’s eye, the stone will divide into 2 distinct colours separated by the eye. Top quality stones will show honey yellow on one side, and yellowish green on the other.
• Does the stone have good transparency?
• Is it clear? Are there surface or internal imperfections that distract the viewer from the eye?
• Is the cutting good? Is the shape pleasing to the eye?

This article has been vetted for accuracy by Marc Brauner, CEO of the International Gemological Institute. (source www.solitaire.com.sg)