 
The Griseous Orb is an exclusive item for Giratina that is currently only found in Pokémon Platinum. This item is the only way to transform Giratina into Origin Forme. When held on to Giratina, it changes to Origin Forme and its Dragon and Ghost type attacks increase in power. The item can only be found if the player has caught Giratina from the Distortion World. If so, it can be found in an alternate part of the Distortion World which can be accessed inside Turnback Cave after the player has solved its puzzle. In Pokémon White/Black it can be obtained from the Shadow Triad on Marvelous Bridge after the story's completion.
Trivia
- The Griseous Orb is actually crystal-like in shape, not spherical like the Adamant Orb and the Lustrous Orb.
- If a Giratina with the Griseous Orb is taken into a battle against a player with Diamond or Pearl, the Griseous Orb will go back to the player's bag. This is probably because Origin Forme is exclusive to Platinum only.