Gem Homeworld

The "Gem Homeworld", or simply "Homeworld", is the home planet of the Gem race. It was first mentioned in "Mirror Gem".

Description
While little is known about the Gem Homeworld, it is clear that it is the original home planet of the Gem race. Its culture is unknown, though Lapis Lazuli states that it is more advanced than it was 6,000 years prior, possessing technology such as the Gem Warship and Gem Destabilizers. This advanced technology greatly contrasts the old and decrepit ancient Gem technology left on Earth.

Going by the information of the Kindergarten, the existence of Gem-controlled planets, and the rebellion led by Rose Quartz in order to protect Earth from the actions of her people and their leader, it would appear that Homeworld clearly has malicious intentions for Earth, and by extension, the entire galaxy. This could possibly mean they are a warlike society bent on wiping out organic life. Another possibility is that they simply don't care about non-gem life forms, seeing them as inferior. The Gems primarily came to Earth for the reasons of war and experimentation. Yellow Diamond is possibly Homeworld's leader, or at the very least, a high-ranking authority figure.

"Mirror Gem"/"Ocean Gem"
Lapis Lazuli desired to return "home", referring to the Gem Homeworld. It can be seen that the Gem Homeworld is within great distance from Earth and that Lapis Lazuli leaves Earth and travels in the direction of these stars to the Gem Homeworld.

"Space Race"
Pearl mentions that the Galaxy Warp served as a method of transport to Homeworld, via the now inactive Homeworld Warp.

"Warp Tour"
The Gem Homeworld is mentioned by name, and Peridot warps to Earth from there. Homeworld's Warp Pad is repaired by Flask Robonoids in order for Peridot to perform a maintenance check. Upon her departure, Garnet destroys the Warp Pad with her gauntlets, once again preventing travel to and from Homeworld.

"On the Run"
Amethyst reveals that Homeworld Gems created other Gems in a facility known as the Kindergarten. Amethyst, among many other Gems, is one of these creations.

"The Message"
Lapis Lazuli states that Homeworld is much more advanced, and she doesn't understand any of it. She contacted the Gems with technology that could communicate with the Wailing Stone, but only with help from Greg.

"The Return"/"Jail Break"
The Gem Warship, transporting Jasper, Peridot, and Lapis Lazuli, was dispatched to earth from Homeworld. It was to return to Homeworld before it crashed back on earth.

"Friend Ship"
An Ancient Gem Colony Ship is visited by the Crystal Gems. Such ship were the fastest way to travel between Earth and Homeworld before the building of the Warp Pads.

"Catch and Release"
Peridot had attempted to repair the Homeworld Warp again, successfully collecting all the pieces of the Warp Pad. Unfortunately, without her Flask Robonoids, she was unable to repair it completely.

"When It Rains"
Peridot reveals that it doesn't rain on the Gem Homeworld. According to her, the Homeworld saw the Earth as unneeded and decided to use it for experimentation, apparently several centuries ago. One such experiment is the Cluster, composed of millions of Gem Shards. It is currently incubating in the Earth's core, but when it emerges, it will be big enough to destroy the planet. The only way to survive would be to destroy the Cluster before it hatches or to get off the planet.

"Back To The Barn"
Homeworld was mentioned by Peridot, saying that pearls are servants on Homeworld.

Caste System
Homewolrld maintains a strict caste system, each gem, or type of gem, is preditermened to suit a certain role, and with it earns a place in the social pyramid and its previledges, defined by the type of gem they are. Any gem who refrains from behaving as their class sugests will be considered defective. The so far known roles and class placing are:

Pearls
Pearls are the servant caste within the Gems' social division. It is known there are hundreds of Pearls in Homeworld, to suit the main role of a servant, described by Peridot as "someone's shiny toy", treated as butlers that only serve to hold things and be submissive and obidient.

Quartzes
The "Guide to the Crystal Gems" booklet reveals that, instead of being seperate gem groups, gems like Amethysts or Jaspers (who are designated as quartz in real life) will fall under the Quartz group. It is so far unknown what their role in the caste system is, though it can be assumed they serve as army gems or soldiers, due to Jasper's warrior status and Amethyst's more physical take during battles.

Peridots
Peridots serve mainly as technicians and take specific charge over Kindergartens. Their exact role is unknown, however they're higher than Pearls and, as seen with Peridot's relationship with Lapis Lazuli and Jasper, are assumed to be more previledged than, at least, Quartzes, as Jasper serves as her escort.

Inhabitants

 * Gems (Homeworld Gems)
 * Yellow Diamond

Former

 * Pearl
 * Garnet (Ruby/Sapphire)
 * Rose Quartz
 * Malachite (Lapis Lazuli/Jasper)
 * Peridot

Trivia

 * Homeworld invaded Earth and established Kindergarten about 6,000 years prior to the events of the show, but was driven off by the Crystal Gems' war of rebellion 5,000 years ago. Based on the numbers given, they occupied Earth for at least a thousand years.
 * Peridot was the first known Homeworld Gem to come to Earth since the war.
 * It is unknown if the planet has an actual name, as up to this point it has only been referred to as "Homeworld".
 * Pearl said that Earth was not a Gem-controlled planet, possibly inferring that some planets are under Gem occupation.
 * Later, in "Cry for Help", Peridot states that Earth is a part of the "Crystal System", suggesting that the Homeworld has incorporated its colonized worlds into a larger territorial body, as well as has categories for star and solar systems.
 * This might be where the Crystal Gems derive their group name from.
 * It is revealed in "On the Run" that Amethyst is not from Homeworld, and instead was created in the Kindergarten.
 * This makes her the first revealed Crystal Gem to be formed on Earth. This is not counting Steven, who was born instead.
 * All Homeworld gems wear a diamond on their outfit, instead of a star like the Crystal Gems. This fits in with Ronaldo Fryman's "Great Diamond Authority" theory.
 * It's implied by Garnet in her verse of the extended theme that living as a fusion on Homeworld may be a practice that's looked down upon, which could be the reason why she would side with the Crystal Gems in the rebellion.
 * This is supported by Jasper's comments upon Garnet during both "The Return" and "Jail Break".
 * Peridot also supported this theory by calling Garnet "filthy war machine", implying that fusions on Homeworld are solely used for war.
 * It's revealed in "When It Rains" that it doesn't rain on Homeworld, since Peridot was not familiar with the phenomenon.
 * Peridot reveals in "Back to the Barn" that Homeworld is a caste society.
 * Implied by Peridot in "Back to the Barn", Homeworld hasn't invented the wheel.
 * A Peridot with a Pearl servant is apparently an unheard of thing on Homeworld.