Wondrous Item Uncommon (950 gp)
Each of these gems contains a mote of elemental energy. When you use an action to break the gem, an elemental is summoned as if you had cast the conjure elemental spell, and the gem’s magic is lost.
Blue Sapphire: Summons an air elemental.
Emerald: Summons a water elemental.
Red Corundum: Summons a fire elemental.
Yellow Diamond: Summons an earth elemental.