A moonstone is a semi-precious gemstone worth about fifty crowns.1 Polished, it takes on a milky, bluish sheen, and it is usually cut cabochon for jewelry and ornament.
Uses
The coven at the Sisters' farm prays with moonstones, in a way like the prayer stones of the dwarves in the sealed vaults.2
History
Session 12
In a dwarven shrine in the sealed Underforge Vaults beneath Argentum, Hazel told the party that the Sisterhood prays much as the dwarves had with their prayer stones, but with moonstones. She had none with her, and Luma offered to make her a stone.2