Gems are an alien race from a number of planets. Some gems , such as Homeworld gems, still have a motive to "do bad things" to Earth. All gems can[[Crystal Gem Weapons| ]] [[Crystal Gem Weapons|summon weapon]]s, [[Fusion Gems|fuse]] , shape-shift themselves and clothing, retreat to their gems to regenerate, and do not age but can still become hurt and die. Not much is known about gems from other planets.