Gold Diamond

Gold Diamonds are found in Luigi's Mansion, worth 20,000,000G each, which is most of any collectible in the game. They are significantly larger than Silver Diamonds and Red Diamonds.

Gold Diamonds are found in two spots. In the first one, Luigi must water a plant three times in the Boneyard (where Spooky resides): once when he first sees it, once after defeating Bogmire, and once after defeating Boolossus to make the now-flower bloom, revealing the diamond and several other treasures. The other can be found if Luigi captures all 50 Boos (not counting King Boo); the last Boo drops the Gold Diamond.