Cat’s Eye Quartz and Diamond ring, late 19^th century. The unusual cabochon stone at the centre of this ring shows a flash of light across its surface. Known as ‘chatoyancy’ or ‘cat’s eye effect’, this rare phenomenon is only found in a few stones, most notably chrysoberyl and quartz, and is caused by thousands of long, needle-like inclusions appearing alongside each other, reflecting a line of light that rolls across the stone as it is rotated. This Cat’s Eye Quartz has been set within a border of charming hand-cut 19^th century cushion-shaped diamonds, to a subtly Baroque-style mount with scrolled shoulders – a perfect finishing touch to this beautiful Victorian ring.