Strong's G4557 — σαρδόνυξ (noun)
sardonux (sar-don'-oox) n.
1. a "sardonyx", i.e. the gem so called
[from the base of G4556 and onux "the nail of a finger", hence the "onyx" stone)]
KJV: sardonyx 
Root(s): G4556 
Hebrew root: σάρδιος
Occurrences: 1