Zircon Gem

Zircon Gems are valuable gems in the game which may be found. This item appears in Baldur's Gate, Baldur's Gate: Enhanced Edition, Baldur's Gate II: Shadows of Amn and Baldur's Gate II: Enhanced Edition.

In-game description
"Zircon is a brownish crystal found in igneous (volcanic) rocks. Zircon attains its pale blue shade with heating and cutting (usually facet-cut)."