Elemental gem

An elemental gem is a gem containing a mote of elemental energy. It can be used once to summon an elemental as if by the Conjure Elemental spell, after which the magic is lost.

Description
The elemental gem's type determines which elemental it summons. Blue sapphire will summon an air elemental; yellow diamond an earth elemental; red corundum a fire elemental; and emerald a water elemental.

History
The Mighty Nein found a red corundum elemental gem cut into a square shape in the Bag of Holding they found at the Sour Nest. Caleb identified it and gave it to Beau, who held on to it until finally using it to summon a fire elemental in the fight against Thelashas in the Folding Halls of Halas.