size: 5.25 weight: 10 grams material: platinum gemstone: cat's eye tourmaline: 6.789ct diamonds: 0.48ctw, G-H color, SI clarity Notes from the Curator Chatoyancy in tourmaline—a rare optical phenomenon within an already varied gem family—arises from parallel fibrous inclusions that reflect light in a single traveling band, focused into a bright "eye" when the stone is cut cabochon. This specimen, carrying nearly seven carats of deep olive-green cat's-eye tourmaline in a platinum mount flanked by near-half-carat diamonds, offers the collector a strong chatoyant effect in a substantial scale. Tourmaline's coarse tube structures can produce a very strong cat's-eye, and the sharpness of the eye depends on the alignment and density of those internal tubes; proper orientation at the cutting stage is crucial to centre the band and maximise the phenomenon across the dome. The deep green coloration suggests iron-rich chemistry, typical of darker tourmaline varieties, and the cabochon's faceted diamond accents in platinum situate it within the mid-twentieth-century tradition of statement cocktail rings that prized phenomenal stones.