Red diamond (Wario World)

"Listen, eventually you're going to have to deal with the Stone Doohickey that sits on the Goal. To get rid of it, you've gotta collect a certain number of red diamonds."

- Spriteling

A red diamond is a treasure from Wario World. Wario needs to gather these treasures from wooden and steel trapdoors in order make the Stone Doohickey guarding the door to the boss of the level disappear. There are eight red diamonds in each level, but Wario only needs three to six of them to get rid of the Stone Doohickey.