From an unused root (probably meaning to freeze); crystal (from its resemblance to ice) -- pearl.
H1378. gabish
גָּבִישׁ noun masculine crystal (compare אֶלְגָּבִישׁ hail — on relation of meanings compare Greek κρύσταλλος, & Ethiopic usage of DiLex. Aeth.759 — Arabic gypsum, Assyrian gibšu, mass, abundance, COT Gloss) — וְגָבִישׁ רָא֯מוֺת Job 28:18 coral and crystal.