A Ghostly Gem is a gemstone covered in dark energy, and looks very similar to a Dark Moon Piece, but has the shape of a diamond. In Luigi's Mansion 3: Haunted Invasion, 10 of them are needed to access King Boo's castle. When you collect all 10 of them, they all stick together and transform into a key.

The first image shows all the 10 Ghostly Gems combined.

The second image shows a Ghostly Gem.

200px-0,382,52,243-RHK This article is a stub. Please help expand it, or Rocko H. Koopa will miniaturize you!

Rocko H.Koopa is not owned by me. It's owned by

Ghostly Gem key

The Ghostly Gems when combined together

Nintendo Drilly.

Ghostly Gem

A Ghostly Gem