Diamond (Wario Land 4)
From the Super Mario Wiki
A Diamond is a treasure found in Wario Land 4. They are each worth 1000 points, and are usually located throughout a level in secret and hard to reach areas, since they are so valuable. They can also be found in Puzzle Rooms (in a Purple Pipe). Collecting them is not essential to progressing in the game, but the player can use the points earned as currency in the Mini-Game Shop.