Cat's-Eye Stones, Explained
Cat's-eye is the stone in the middle of our chandbali, and it is the one people ask about most, usually some version of: what is it, and is it real?
Straight answer first. The stone in our earrings is glass. There is a natural gemstone that shows the same effect and it is expensive; what is used in imitation jewellery is a manufactured fibre-optic glass that reproduces the look deliberately. We would rather say so plainly than let you assume otherwise.
The effect has a name
It is called chatoyancy, from the French for cat's eye. A single bright band of light floats across the surface of the stone, and it moves as you tilt it. It is not painted or printed on - it is an optical effect produced by structure inside the stone.
In a natural gemstone the structure is parallel needle-like inclusions, all lying the same way, each scattering light into a line. Cut the stone as a dome across those needles and the scattered light gathers into a single band.
How the manufactured version works
Fibre-optic glass does the same job by design. Thousands of fine glass fibres are fused into a solid rod, all running parallel, and the rod is cut and domed across the fibre direction. The fibres play the role the needles play in a natural stone, and you get the same travelling band.
The reason it looks convincing is that the physics is genuinely the same. It is not a printed imitation of chatoyancy, it is chatoyancy, produced from a different material.
Why it has to be a dome
The band only appears on a curved surface, and only when the curve runs across the fibres. Cut the same material flat and you get a striped stone with no movement at all.
That is why every cat's-eye you see is a cabochon - domed and polished rather than faceted. It is also why the stone in a chandbali sits proud of its setting: the height is doing the optical work, not just decoration.
Telling manufactured from natural
Three usable signs, none needing equipment.
Colour. Fibre-optic glass comes in bright saturated pinks, yellows, greens and blues. Natural chrysoberyl cat's-eye is essentially honey, brown and greenish-gold. A vivid pink cat's-eye is glass, every time.
Sharpness. The manufactured band is very crisp and very straight, because the fibres are perfectly parallel. Natural stones have slightly irregular inclusions, so the band is often softer or a little uneven.
Price. The decisive one. Natural cat's-eye chrysoberyl is a serious gemstone. Nothing at a costume-jewellery price contains one.
Looking after it
The glass itself is hard and does not scratch easily in normal wear. The vulnerable part is the setting - the stone is held by a bezel, a rim of metal pressed over its edge, and a hard knock can loosen that rim.
Keep it away from ultrasonic cleaners and never scrub around the bezel. Wipe the dome with a dry soft cloth, which is all it needs to look wet and glossy again. Do not soak it: water gets behind the stone where you cannot dry it, and that is bad for the metal even though the glass does not care.
How to wear it
A cat's-eye stone wants light and movement, so it is at its best on an earring rather than a ring. The band shifts every time you turn your head, which is exactly the effect a chandbali fringe is also going for.
Ours comes in pink with turquoise accent stones and yellow with magenta - both set in a pierced oxidised crescent, where the darkened silver makes the stone's glow read brighter than it would against gold. Have a look at the chandbali, or the rest of the range.