אַחְלָמָה ʼachlâmâh (H306)

a gem, probably the amethyst

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.

perhaps from חָלַם (H2492) (and thus dream-stone);