sardonyx

Concise Bible Dictionary:

Chalcedony Var. Agate

Strong’s Dictionary of Greek Words:

Greek:
σαρδόνυξ
Transliteration:
sardonux
Phonic:
sar-don’-oox
Meaning:
from the base of 4556 and ὄνυξ (the nail of a finger; hence the "onyx" stone); a "sardonyx", i.e. the gem so called
KJV Usage:
sardonyx

Jackson’s Dictionary of Scripture Proper Names:

ruddy: (finger) nail colored (?)