| IMPORTANT ITEM|
|Description||The object Koops's father found in Hooktail's belly.|
|Use||Open The Thousand-Year Door, reveal the next Crystal Star, and defeat the Shadow Queen|
|To||Thousand-Year Door Pedestal|
|Other Edition||Unknown edit|
The Diamond Star, like the other Crystal Stars, was created by the Shadow Queen as powerful objects she could use to rule the world. It somehow ended up in Hooktail Castle, and the rumor of Hooktail guarding a fabulous treasure began to spread. Many adventurers and treasure-seekers, including Koopley and Professor Kolorado's father, left to look for the trasure, but all were defeated by the Dull Bones or Hooktail herself. Professor Kolorado's father was defeated in the hallways, presumably by the Dull Bones, while Koopley was actually swallowed alive by Hooktail. Later, in his quest for the Crystal Stars, the location of the Star was revealed to Mario, and he set out to find it. He passed all obstacles in his way, and successfully defeated Hooktail. She then coughed up Koopley, who had found the Diamond Star while he was trapped in her stomach. He gives the Star to Mario, as a gift and reward for saving him. Mario takes the Star back to The Thousand-Year Door, and holds it aloft. The Star glows brightly, and reveals the Boggly Woods on the Magical Map, the location of the Emerald Star. The Diamond Star, along with the other six Crystal Stars, later go to everywhere Mario had traveled to rally support. The Diamond Star went to Petalburg, and many of the Koopas there cheer him on.
After Mario obtained the Diamond Star, more skills became available to him. His Star Point capacity increases from one to two, and he learns the new move Earth Tremor. It also gives him one less Crystal Star to look for.
| Diamond Star | Emerald Star | Gold Star |
Ruby Star | Sapphire Star | Garnet Star