Perhaps from H2492 (and thus dreamstone); a gem, probably the amethyst
KJV Usage: amethyst.
Brown-Driver-Briggs' Hebrew Definitions
1. amethyst, a gem in the third row on the ephod, breastplate of judgment worn by the high priest. Transliteration of the Septuagint word. Identification is not certain but is a purple stone perhaps a corundum or red or brown jasper.
Origin: perhaps from H2492 (and thus dream-stone)
Parts of Speech: Noun Feminine