How is the diadem of rowena ravenclaw destroyed?

Answer:
Crabbe (one of Draco's friends) starts fiendfyre (cursed fire) in the Room of Requirement. He is trying to kill Harry, Ron, and Hermione. However, the fire gets out of control and consumes the room, destroying the diadem in it.
Contributor: Wyatt
First answer by ID2926336953. Last edit by Daniwill. Contributor trust: 2 [recommend contributor recommended]. Question popularity: 2 [recommend question].