Gem

Gemstones are valuable objects found in Luigi's Mansion: Dark Moon and Luigi's Mansion 3. They bear a resemblance to Stones from the preceding game, Luigi's Mansion, though these items serve as collectibles rather than containing a value of gold. In Luigi's Mansion: Dark Moon, there are thirteen Gemstones hidden in each of the five mansions in the game, making a grand total of 65 Gemstones in the entire game. Amethysts are found in Gloomy Manor, emeralds are found in Haunted Towers, rubies are found in Old Clockworks, sapphires are found in Secret Mine, and diamonds are found in Treacherous Mansion. The coloration of the five sets of thirteen Gemstones corresponds to the theme of the five mansions. Unlike the Red, Blue, and Gold Diamonds found in the original game, Gemstones do not function as a form of currency but rather as a collectible. Once the player has collected all thirteen Gemstones in a mansion, they will be rewarded with one of five different statues of Luigi with the Gemstones encrusted in the stand. The player can see the Gemstones they have collected inside the Vault, on the mansion select screen, when one is collected in a mansion, and when the totals and records are displayed at the end of a mission. Any statues that have been unlocked can only be viewed inside the Vault.

Some Gemstones can be obtained in any mission, while some can be obtained only in a specific mission or once certain conditions have been met.

In Luigi's Mansion 3, there is one blue, one green, one white, one purple, one yellow, and one red gem per floor, making a total of six gems per floor. The gems will be a different shape depending on the floor. The gems on B2 (Boilerworks) are shaped like wrenches. The gems on floor B1 are square. The gems in the main lobby are shaped like diamonds. The gems on the fifth floor (RIP Suites) are a rectangular shape. The gems on the second floor (Mezzanine) have an oval shape. The gems on the third floor (Hotel Shops) are shaped like teardrops. The gems on the fourth floor (The Great Stage) are shaped like quavers. The gems on the sixth floor (Castle MacFrights) are shaped like swords. The gems on the seventh floor (Garden Suites) are shaped like flowers. The gems on the eighth floor (Paranormal Productions) are shaped like film reels. The gems on the ninth floor (Unnatural History Museum) are shaped like T-rex prints. The gems on the 10th floor (Tomb Suites) are shaped like snakes. The gems on the 11th floor (Twisted Suites) are shaped like dice. The gems on the 12th floor (The Spectral Catch) are shaped like a skull and crossbones. The gems on the 13th floor (Fitness Center) are shaped like dumbbells. The gems on the 14th floor (Dance Hall) are shaped like headphones. The gems on the 15th floor (Master Suites) are shaped like King Boo.

Luigi's Mansion: Dark Moon

 * Instruction manual description: "If you collect all the gems, something neat may happen!"