In Despicable Me 3, what is the name of the diamond Gru and Lucy try to recover from Balthazar Bratt?

In Despicable Me 3, Gru and Lucy try to recover the Dumont diamond from Balthazar Bratt.

The Dumont diamond is the valuable gem stolen by Balthazar Bratt during the film’s opening heist. Gru and Lucy pursue Bratt after the Anti-Villain League dismisses Gru, and the diamond becomes one of the objects linking their mission to Bratt’s larger revenge plan.

This diamond is unrelated to Gru’s plan in the first film to steal the Moon. It is also separate from the ruby featured in Minions, which Scarlet Overkill and the Vicious 6 seek. The jewel’s name comes from the Dumont Museum setting associated with Bratt’s theft.