Gems

Gems are an extraterrestrial species of magical beings that play the main role in Steven Universe. Their origin is unclear, but it is likely that White Diamond established the Diamond Authority, which then went on to create Homeworld and thus more of these Gems have been created. 5,750 years ago, Homeworld maintained numerous outposts on Earth, but the process was disturbed by the Crystal Gems, and consequently Homeworld fled, leaving the Crystal Gems and many Corrupted Gems on Earth.