Elemental gem

Elemental gems were gems that had been attuned to one of the Elemental planes and were infused with the power to summon elementals.

Description
Gems that could be enchanted to become elemental gems included yellow diamonds, red corundums, emeralds, and blue sapphires.

Powers
Upon breaking or shattering, an elemental gem released its magic and allowed its wielder to summon an elemental in a similar way to a conjure elemental or summon nature's ally spell. Depending on the gemstone, a different elemental would be summoned: yellow diamonds summoned earth elementals, red corundums summoned fire elementals, emeralds summoned water elementals, and blue sapphires summoned air elementals.

Once broken and used, the gem lost its power.

Appearances

 * Adventures
 * Baldur's Gate: Descent into Avernus