Pearl

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

In-game description
"Pearls consist of layers of aragonite agonizingly formed around a bit of grit or other irritant inside oysters and other mollusks. The resulting pearl has a rich, deep luster. Most of the pearls in the realms are white, however there are varieties that are much more rare such as rainbow and black."

Baldur's Gate II: Shadows of Amn
Limited Wish can create pearl.