size: 16 x 8mm weight: 1.25 grams material: platinum gemstones: natural cats eye chrysoberyl 1.28ct natural diamonds: 0.30ctw, VS-SI, G-H Notes from the Curator Cat's eye chrysoberyl — formally known as cymophane — displays chatoyancy, a sharp band of light that glides across the stone's surface when moved, the result of parallel rutile needle inclusions reflecting light at right angles to their orientation. Chrysoberyl produces the most distinct cat's-eye of any gemstone, so definitive that the term "cat's eye" used alone, without naming another species, refers exclusively to chrysoberyl by convention. The most prized specimens from Ceylon show a honey-gold to greenish-yellow body that, under a strong side light, divides into a milky white half and a honey-gold half with the eye running cleanly between — the "milk and honey" effect, specific to chrysoberyl with the right trace chromium and iron content. Cat's eye chrysoberyl has the longest history of gems in the chrysoberyl family, treasured in Asia before the birth of Christ and known in Rome by the end of the first century; in the symbolic necklace of Vishnu, a green cat's-eye chrysoberyl represented the magnetic center of human passion, and its popularity surged in the nineteenth century after the Duke of Connaught presented his fiancée with a cat's-eye betrothal ring. This 1.28-carat oval cabochon, mounted in platinum alongside near-colourless diamonds in an open claw setting, exemplifies the enduring twentieth-century taste for phenomenal gems framed in light white metal.