onyx: [13] Greek ónux meant ‘claw, fingernail’ (it is distantly related to English nail). Certain sorts of onyx are pink with white streaks, and a resemblance to pink fingernails with their paler crescent-shaped mark at the base led the Greeks to name the stone ónux. The word travelled to English via Latin onyx and Old French onix. => nail[onyx etymology, onyx origin, 英语词源]
1873, "one who professionally treats hands and fingernails," from French manicure, literally "the care of the hands," from Latin manus "hand" (see manual) + cura "care" (see cure (n.1)). Meaning "treatment and care of the hands and fingernails" is attested from 1887.