Crown (King Boo)

King Boo's Crown, generically referred to as crown, is the final piece of jewelry Luigi collects before he saves Mario in Luigi's Mansion. In Luigi's Mansion, the crown holds a red diamond at the top. Officially, King Boo's Crown also counts as a Red Diamond, making it worth the same amount as a single coin. King Boo's Crown is the only unit of money in the game that must be collected, so it is possible but unlikely to get only 5,000G the entire game.

The crown has changed in the later Super Mario games it has appeared in. In almost all of King Boo's appearances outside the Luigi's Mansion series starting with Mario Kart: Double Dash!!, it is shown as a golden crown encrusted with jewels like Peach's Crown, with four red ones encrusted around the crown and one blue one in the center. In Luigi's Mansion: Dark Moon, however, King Boo appears to sport the crown's initial appearance, except the gem, which is now a glowing purple diamond-shaped stone that resembles an amethyst, matching King Boo's color theme. This gem gives him enough power to shatter the Dark Moon.

The crown returns in Luigi's Mansion 3, alongside its owner. It largely has the same appearance as in Dark Moon, although it is given a bit more detail. After defeating King Boo, Luigi manages to gain the gem. However, after The Last Resort collapses and Professor E. Gadd's containment field is breached, the gem vanishes, causing the volatile ghosts to return to their senses.