Search
Cat's Eyes
Specimen | Catalog Number | Locality | Weight |
---|---|---|---|
Scapolite | NMNH G2161 | Myanmar [Burma] | 3.29 ct |
Chrysoberyl | NMNH G3924 | Sri Lanka | 171.50 ct |
Elbaite | NMNH G5700 | Brazil, Minas Gerais | 65.50 ct |
Beryl | NMNH G3248 | Madagascar | 43.51 ct |
Elbaite | NMNH G3119 | Brazil, Minas Gerais | 53.20 ct |
Scapolite | NMNH G3301 | Myanmar [Burma] | 29.90 ct |
Elbaite (var. rubellite) | NMNH G3786 | United States, California | 17.50 ct |
Gems exhibiting a single bright band are called cat's eyes. This optical phenomenon, called chatoyancy, is caused by light reflecting off of parallel bundles of tiny hollow tubes or fibrous crystals of another mineral inside the gemstone. When a stone is cut into a cabochon (domed top, flat bottom) the reflected light is focused into bright bands on the surface that are perpendicular to each set of fibers or hollow tubes.Many minerals can sometimes be cut as cat's eye gems. Clockwise from top: 171.6ct cat's eye chrysoberyl from Sri Lanka is one of the largest of its kind; a green elbaite gem (53.2ct) from Brazil; a pink elbaite gem (17.5ct) from California; a spectacular teal-colored elbaite gem (65.5ct) from Brazil that forms its cat's eye as light reflects off of parallel grooves, or striations, on the back side of the stone that were on the original crystal surface: two scapolite gems from Burma, one a white stone (29.9ct) and the other purple (3.3ct); and a stunning golden beryl (43.5ct) from Madagascar.