A red diamond is an item in Wario World.
In Wario World[]
Red diamonds are a type of treasure found in the sub-levels accessed from wooden and steel trapdoors. Wario has to collect the red diamonds so that the Stone Doohickey guarding the door to the level's boss disappears.
Although each level has eight red diamonds, not every one has to be collected to get rid of a level's Stone Doohickey, and the two levels of each world have a minimum requirement of red diamonds that increases by one in the next two levels of a world: Excitement Central's levels, Greenhorn Forest and Greenhorn Ruins, require at least three red diamonds; Spooktastic World's levels, Horror Manor and Wonky Circus, require at least four; Thrillsville's levels, Shivering Mountains and Beanstalk Way, require at least five; and lastly, Sparkle Land's levels, Mirror Mansion and Pecan Sands, require six red diamonds.