Onyx
Archimandrite Nikifor’s Biblical Encyclopedia
(in Hebrew, shoham, otherwise sardonyx) (Gen. 2:12, Ex. 28:9, 20)—one of the precious stones, highly prized as an ornament. It occupied the second place in the fourth row of stones on the high priest’s breastplate of judgment. The stone is usually green with whitish lines, though onyx also occurs in a pale color resembling that of a fingernail.