Chrysoberyl and Diamond Ring. ‘Cat’s eyes’ are so-named because of the narrow flash of light across their centres, resembling a cat’s pupil. This optical effect is caused by light reflecting off many microscopic needle-like inclusions in the stone, all aligned in the same direction, and is revealed when the stone is cut as a cabochon. While this phenomenon is known in a few stones, for the stone itself to qualify as a proper ‘cat’s eye’, it must be a chrysoberyl. These historic gems, with their charming spectrum of colour that runs from pale yellows to golden browns to green, are famed for producing the best examples of this effect. An ideal cat’s eye should be a narrow flash of bright light, which runs across the centre of the stone. The narrower, brighter and more central the band of light, the finer the stone. This ring is set with a trio of these captivating and alluring stones, and the centrepiece is a particularly fantastic example. spaced by a pair of charming antique cushion-shaped diamonds, claw-set in yellow gold, this hypnotic jewel would be an excellent choice for an engagement ring, sure to fascinate for years to come.