The term "sardonyx" originates from the ancient Greek word "sardonux" (σαρδόνυξ), which is a combination of "sard" (σάρδιος), a reddish-brown chalcedony, and "onyx" (ὄνυξ), which means "fingernail" or "claw". They thought this layered stone resembled a fingernail and fingertip. A horse's hoof is made of keratin, much like our fingernails. Was the Victorian jeweler who made this piece aware of all this? Probably not. My job is weird.
MATERIALS: 14k gold (tests), sardonyx, new 14k gold chain,
AGE: c. 1870
SIZE: 1 1/8" length including the bale, 3/4" width, 18" chain.