Diamond Star

The Diamond Star is the first of the Crystal Stars Mario collects in Paper Mario: The Thousand-Year Door. Some time after the four heroes sealed the Shadow Queen using the Crystal Stars, the dragon Hooktail got ahold of the Diamond Star and kept it in her castle. During their quest, Mario and his partners traverse Hooktail Castle and defeat Hooktail in hopes of recovering the stolen Diamond Star. Upon defeating her, Hooktail spits out Koops's father, Koopley, who gives Mario the Diamond Star. The Diamond Star also teaches Mario the move Earth Tremor to use in battle.

Trivia

 * The Diamond Star and the Gold Star are the only Crystal Stars that aren't from a Chapter that involves the X-Nauts or the Shadow Sirens in any way.