The Gem Homeworld maintains a strict caste system with every type of gemstone having a predetermined role and place in the social pyramid, each with own their privileges and ordained purposes. Any Gems who in any way deviates from their roles, be it intentional or not, would be considered defective. Since the penalties for such actions are so severe, most disgruntled Homeworld Gems either keep their dissensions to themselves or are forced to go into hiding. Because there are so many of one type of Gem, all Homeworld Gems — except the Diamonds — distinguish themselves via coded serial numbers.
- Main article: The Great Diamond Authority
Diamonds are the highest-ranked caste similar to royalty and referred to as the "matriarchs" of Gem society; they make up the Great Diamond Authority. All diamonds are of a massive size, towering over other types of Gems seen and even some fusions. They all have diamond-shaped pupils in their eyes.
Almost all Homeworld Gems are fanatically loyal to the Diamonds, seeing as how Peridot 5XG formerly adored Yellow Diamond. Gems also appear to be categorized under their respective Diamonds as Blue Diamond referred to Sapphire as being "of her court" and Peridot saying she was "made" for Yellow Diamond. Any form of infidelity displayed towards the Diamonds is considered punishable by death at the worst. Their honorific (from their subordinates) is "My Diamond."
There appears to be a caste ranking within the Diamonds themselves as White Diamond was shown to be hierarchically superior to the other Diamonds and the leader of the Authority. Conversely, Pink Diamond was below Yellow and Blue Diamond and had to obey their orders.
- White Diamond - First truly appearing in "Legs From Here to Homeworld", she is the leader of the Diamond Authority.
- Yellow Diamond - First truly appearing in "Message Received", she is the commander-in-chief of Homeworld's military.
- Blue Diamond - First truly appearing in "Steven's Dream", she is the overseer of Homeworld's diplomacy.
- Pink Diamond/Rose Quartz - Mentioned in "Earthlings" and first truly appearing in "Jungle Moon", she was the leader of Earth's colonization before being allegedly shattered at the hands of a Rose Quartz during the Rebellion. In reality, she took the identity of a Rose Quartz and staged her death in hopes of removing Homeworld's presence on Earth.
Emeralds are high-ranking Gems with authority. In the Steven Universe Podcast, Rebecca Sugar and Ian Jones-Quartey emphasize that Emeralds (specifically the one seen in "Lars of the Stars") are elite Gems known to be in charge of fleets. The only Emerald shown owns three ships (her own personal shuttle, the Sun Incinerator and Destiny Destroyer) and is in charge of an unspecified amount of Gems.
- Emerald - An Emerald whose ship was stolen by Lars Barriga and the Off Colors, who she has been following ever since in her imperial warship to reclaim her most prized starship from them.
- Main article: Sapphires
Sapphires are of the nobility class, described as being rare aristocratic gems and part of the "elites"; in spite of this, they have no immunity from potential outcast status. They can see into the future using their "future vision". So far, Sapphires are the only non-fusion gem type shown with this ability. However, defective Sapphires, an example being Padparadscha are only able to have visions of events slightly in the past. Their honorific is "Your Clarity".
- Sapphire - A Sapphire sent to Earth as a diplomat to attempt to disband the Rebellion and now a current member of the Crystal Gems.
- Padparadscha - An "off-color" Padparadscha Sapphire deemed defective for her ability to only predict events that have already occurred.
- Pink Diamond's Unknown Sapphires - Sapphires who used to belong to Pink Diamond first mentioned by Blue Zircon in "The Trial".
- Homeworld Sapphires - Various Sapphires who attended the "Era 3 Ball".
While the exact role of a Garnet is unknown, they seem to be high-ranking, as the only Garnets seen are Hessonites in charge of lower-ranking Gems. Types of Garnets include Hessonites, Demantoids, and Pyropes, as mentioned by Blue Diamond in "Together Alone". The Crystal Gem Garnet seems to have no relation to this caste despite sharing a name, as Blue Diamond is surprised to hear that she calls herself one.
While the exact role of a Hessonite is unknown, they are named commanders in charge of lower-ranking Gems. The only Hessonite seen in the series is Nephrite's (the Centipeetle Mother's) commander. She issued Nephrite the order to initially travel to Earth and later to retreat from the incoming Diamond attack. The first Hessonite introduced into the series canon as a whole is the main antagonist in Save the Light. Some Hessonites are tall and orange with poofy hair.
- Hessonite - A Hessonite who is the main antagonist in Save the Light, the superior of "Squaridot" and former owner of the Light Prism.
- Nephrite's Commander - A Hessonite that commanded Nephrite and her crew at least from the colonization of Earth until the end of the Gem War. Her gemstone is situated on her chest.
While the exact role of a Morganite is unknown, they are known to be one of many in charge of lower-ranking Gems. One Morganite is mentioned by Rhodonite to have, at some point replaced Rhodonite's components after discovering they liked to fuse.
- Unknown Morganite - A Morganite mentioned to have replaced and exiled Rhodonite's components after discovering they enjoyed fusion with each other.
According to Pearl (as well as Aquamarine's own gloating), Aquamarines seem to have a high rank in Homeworld's hierarchy. Rebecca Sugar says that Aquamarines are one of the very high-ranked blue Gems on Homeworld.
- Aquamarine - An Aquamarine sent to Earth as a bounty hunter by the Diamonds in order to retrieve different human "variations" for display in Pink Diamond's Zoo.
- Homeworld Aquamarines - A group of Aquamarines seen celebrating the return of the Diamonds in "Legs From Here to Homeworld" and attending the "Era 3 Ball" in "Together Alone".
The Topazes' roles seem to be that of soldiers, obeying orders and acting as bodyguards for their assigned Gems. A fusion of two Topazes was sent to Earth by the Diamonds alongside an Aquamarine to retrieve different "variations" of human beings for Pink Diamond's human zoo. These Topazes are incredibly efficient at trapping and engulfing victims within their fusion-form. Topazes also act as guards over entrances of certain places suitable for Elite Gems, as seen in "Familiar". Rebecca Sugar says that Topazes are high-ranking yellow Gems. However, they are not as highly-ranked as Aquamarines.
- Yellow Diamond's Topazes
- Topazes (left and right) - Two Topazes sent to Earth by the Diamonds as a fusion in order to retrieve different "variations" of humans for Pink Diamond's Zoo.
- Chamber Guards - Two Topazes who stand guard outside Yellow and Blue Diamond's Chambers.
- Blue Diamond's Topazes
As stated by Yellow Diamond, Lapis Lazulis are made for terraforming. Peridot also said that Lapis Lazulis are typically partial to water and flying. It is unclear how high they rank in the caste system, though they seem at least equal to or higher than Peridots.
The Lapis Lazulis' use for terraforming planets likely explains Lapis Lazuli's ability to manipulate massive bodies of water with ease (and possibly explains her enjoying farming).
- Lapis Lazuli - A Lapis Lazuli who was trapped in a mirror for thousands of years and ultimately used by the Homeworld Gems for their invasion of Earth. She was eventually freed from the Mirror by Steven and is now a Crystal Gem.
- Main article: JadesWhile their exact role has not been shown, Jades appear to be high up in the caste given that they attended the Era 3 Ball. Unlike other Homeworld gems, Jades can have quite distinctive differences between their physical appearances.
- Homeworld Jades - Various Jades who attended the Era 3 Ball.
- Fusion Jades - Two Jades who fused after seeing Stevonnie, Garnet, and Opal. As a result, Yellow Diamond poofs them.
Bismuths are a building caste in charge of constructing temples, spires, arenas and other structures for aristocratic members of Gem society on Homeworld's Gem colonies. As such, they possess a broad stature for intensive physical labor, above-average resistance to heat and damage and hands capable of fluidly changing form without the need for typical Gem shapeshifting to fit a wide variety of purposes.
- Bismuth - One of the original Crystal Gems who was poofed and bubbled by Rose Quartz and later Steven when she developed a weapon devised to shatter Pink Diamond, unaware that Rose and Pink were one and the same. She permanently rejoined the team after "Made of Honor".
- Unknown Bismuth - A Bismuth that appeared in a flashback in "Same Old World". She was the one who poofed Lapis Lazuli during the Rebellion.
Nephrites are in charge of piloting Homeworld Dropships to begin colonizing other planets and may also serve as pilots for various other types of ships. Their rank in the caste system is never clearly stated but appears to be high considering they captain their own ships and Yellow Diamond was shown to contact a Nephrite captain directly in "Jungle Moon", something she would not do with a lower-ranking Gem. Numerous Nephrites were corrupted with one (known as "Centipeetle") formerly being a captain in charge of other Nephrites (in command of a dropship that went to Earth). These Gems flew in Gem spaceships and started building structures on Gem colonies.
- Nephrite Facet-413 Cabochon-12 ("Centi") - Known as "Centipeetle" or "Centi" while corrupted, she was a Gem sent from Homeworld to start building the colony on Earth. However, she got caught in the war and was ordered to retreat. She was unable to board her ship in time and suffered from the attack caused by the Diamonds, resulting in her corruption.
- Nephrite's Crew - A group including two Gems that appear in "Monster Reunion" who became corrupted by not evacuating Earth and not leaving their captain behind. As of now, they all live together in the Ancient Gem Colony Ship.
- Unknown Nephrite - Pearl once took a Nephrite out of the cockpit of a dropship during the Rebellion.
- Hessonite's Nephrites - A group of Nephrites working on Hessonite's warship. They are said to be performing a drill at the time of the Crystal Gems' arrival to the ship. They are mentioned in Save the Light.
- Nephrite Facet-XJ Cut-763 - A Nephrite who works for Yellow Diamond. In the flashback from "Jungle Moon", she shows hesitation for doing her job as the planet they are terraforming has organic life; Yellow Diamond ignores her complaints and demands for her to do her job or else she will shatter her and her crew personally.
Peridots serve mainly as technicians and Kindergarteners, sometimes performing field assignments on other planets such as the Peridot who befriended Steven. Their exact rank is currently unknown; however, they are higher than Pearls (but not high enough to have a Pearl of their own). Era 2 Peridots are given Limb Enhancers to compensate for their lack of abilities older Gems have due to the depletion of resources on Homeworld. One Peridot so far has been shown to have telekinetic control-abilities over metallic objects.
- Peridot Facet-2F5L Cut-5XG – A former Yellow Diamond court member and current member of the Crystal Gems.
- "Squaridot" - A subordinate of Hessonite who appears in Save the Light, nicknamed "Squaridot" for her square hair. She is currently bubbled.
Zircons act as lawyers for the courts of the Gem Homeworld. They presumably have no choice over what cases they prosecute or defend for (as revealed in "The Trial") and are assigned cases instead. In the Steven Universe Podcast, Rebecca Sugar and Ian Jones-Quartey say they have a sort of medium rank on Homeworld, serving the upper class but really having no individual power.
- Blue Zircon - A Zircon who defends Steven during his trial.
- Yellow Zircon - A Zircon who acts as the prosecutor during Steven's trial.
- Main article: Quartzes
Quartzes are a soldier caste. Made to fit the role of an elite warrior, Quartzes have incredible height, broad shoulders and an intimidating muscular build. Rose Quartz and Jasper both fit this description. Amethyst is also a Quartz although she does not fit the description because she "stayed in the ground too long" and was therefore overcooked. Some Quartzes are used as bodyguards and escorts as shown in Jasper's case. They appear to be less numerous than Rubies. According to Ian Jones-Quartey, some have defensive powers as well (like Rose's) since "they can't all be tanks." Quartzes are described as being "huge, loyal soldiers". Jasper stated that Quartzes are made to fight and that Jaspers specifically always get what they want. Some Quartzes also act as guards at Homeworld outposts such as Pink Diamond's Zoo. They were commonly made on Earth. Quartzes are the most diverse known Gem type with Gems including Amethysts, Carnelians, Jaspers and Rose Quartzes.
Other Quartz types include Agates, who rank higher than most Quartzes and seem to be administrative in nature and Citrines, who seem to be an elite caste of guards (including Emerald's sixty-seven elite Citrine guards and Hessonite's Citrine guards in Save the Light).
So far, Holly Blue Agate is the only Agate shown in the show. She is in charge of a group of Quartz soldiers and manages Pink Diamond's Zoo. Quartzes of her type seem to have a higher ranking than standard "made-for-battle" ones. Their purpose seems to be administrative in nature. Yellow Diamond states in "What's the Use of Feeling (Blue)?" that they are meant to be terrifying figures that intimidate Gems under them into obedience. In "The Trial", it is revealed that they can also be bodyguards for high-ranking Gems, such as a Diamond. It can be assumed that, based on the way Holly Blue Agate acts around Sapphire, that Agates, while having some authority, are not very high-ranking Gems, or at least not as highly ranked as Sapphires.
- Holly Blue Agate - An Agate who manages Pink Diamond's Zoo.
- "Crazy Lace" - An Agate who was originally a member of the Crystal Gems.
- Pink Diamond's Agates - Agates who used to belong to Pink Diamond, they were her bodyguards during the Rebellion, first mentioned by Blue Zircon in "The Trial".
- Yellow Diamond's Agates - Agates who reside in one of Yellow Diamond's Asteroid Mines and first mentioned by Rhodonite in "Your Mother and Mine".
Citrines are Quartz Gems who seem to be an elite caste of guards and serve high-ranking Gems.
- Emerald's Citrine Guards - A group of sixty-seven elite Citrines who are mentioned to have guarded Emerald's ship, the Sun Incinerator, on the planet Klavius 7.
- Hessonite's Citrine Guards - A group of Citrines who act as guards on Hessonite's warship. They are only heard by the Crystal Gems before their final confrontation with Hessonite, only in the video game Save the Light.
- Newly-Created Citrines - In "Familiar", Yellow Diamond states that she must check the latest Citrine production reports.
Sometime between the start of Rose Quartz's rebellion and Pink Diamond's shattering, every Rose Quartz in existence was bubbled. They currently all reside in Pink Diamond's Chamber in her Zoo. It was stated in "That Will Be All" that Blue Diamond only wished to keep the Rose Quartzes around for the sake of preserving Pink Diamond's legacy while Yellow Diamond wished that every Rose Quartz be shattered, as they then believed one of them was responsible for the start of the Rebellion and the shattering of Pink Diamond, although this is not the actual truth. While being Quartz soldiers, Rose Quartzes are known for their defensive powers rather than the average offensive abilities Quartzes have.
- Unknown Bubbled Rose Quartzes - A large collection of hundreds of Rose Quartzes, inactive and bubbled by the Diamonds after a Rose Quartz allegedly shattered Pink Diamond.
A kind of Quartz Gems with a purple coloring. The Prime Kindergarten on Earth produced Gems of this type. Amethysts act as soldiers or guards, as seen with the Amethysts guarding Pink Diamond's zoo.
- Amethyst Facet-5 Cut-8XM - A defective and short Quartz and current member of the Crystal Gems.
- Pink Diamond's Amethysts - Amethysts created on Earth who were among the first Quartz Gems to emerge from the Prime Kindergarten. Some would later become members of the "Famethyst".
- Amethyst Zoo Guards - A group of Amethysts now serving under Blue Diamond in charge of guarding Pink Diamond's Zoo. Many are from the Prime Kindergarten and are members of the "Famethyst".
- Amethysts Facet-5 Cut-8XG, 8XJ, 8XK, 8XH, and 8XL - Five Amethysts from the same section of the Prime Kindergarten as the Crystal Gems' Amethyst, and members of the "Famethyst".
- Unknown Crystal Gem Amethysts - An unknown group of Amethysts that were formerly members of the Crystal Gems while Bismuth was active. They are currently presumed to be inactive.
- Homeworld Amethysts - Various Amethysts who attended the "Era 3 Ball". They serve Blue Diamond.
A kind of Quartz Gems with a maroon red coloring. The Beta Kindergarten on Earth produced Gems of this type. Based on the Amethysts, it can be presumed that they would be gems of the soilder type as well.
- Carnelian - A defective and short Carnelian guarding Pink Diamond's Zoo, and a member of the "Famethyst".
- Unknown Defective Carnelian - An unknown defective Carnelian mentioned by Peridot in "Earthlings" (presumably the Carnelian listed above).
A kind of Quartz Gems shown mostly to have tangerine skin and reddish-orange markings, however some Jaspers can come in different colors depending on the type of Jasper they are. Similar to Amethysts, they act as either soilders or guards.
- Jasper - An especially powerful Quartz Gem as noted by Peridot in "Earthlings". She is currently corrupted and bubbled.
- Jasper Guards - A group of Jaspers in charge of guarding Pink Diamond's Zoo, and members of the "Famethyst".
- "Skinny" - A defective and tall Jasper guarding Pink Diamond's Zoo, and a member of the "Famethyst".
- Biggs Jasper - A brown-orange patterned Jasper who was one of the original members of the Crystal Gems before being corrupted. Later, she was captured in the Great North by Jasper and was used to attack the Crystal Gems, but ended up being poofed and bubbled.
- Snow Monster - A corrupted turquoise-blue Jasper with pink spots that was captured in the Great North by Jasper, she was forced to fuse with her but she escaped from her.
- Homeworld Jaspers - Various Jaspers who attended the "Era 3 Ball". They serve Blue Diamond.
A type of Quartz which is yet to be seen but has been mentioned by name.
- Tiger's Eye - A corrupted former Crystal Gem mentioned by Bismuth in "Made of Honor", currently bubbled in the Burning Room.
Quartz Gems lacking specific gemstone identification.
- Unknown Quartz Warrior – A Quartz warrior shown to have fought Rose Quartz during in Pearl's flashback through her Hologram Projection in "Sworn to the Sword".
- Beta Kindergarten Quartz Monsters - Various Corrupted Quartz Gems captured and incarcerated for Jasper's Corrupted Gem army and later freed during "Earthlings".
- Three Unknown Blue-Purple Quartzes - Three Quartzes with unknown gemstone placements and names who surrounded Rose and Pearl before they escaped the Cloud Arena. They serve Blue Diamond.
- Main article: Rubies
Rubies are another type of soldier caste. Garnet describes them as "common", seeing as they are all originally identical to one another. They appear to be used as personal escorts and bodyguards for high-ranking Gems. Seeing as they are so numerous, inferred from Ruby's comment of there being "tons" of her, Rubies are considered somewhat unimportant and highly expendable grunts, though they compensate by fusing together into bigger constructs of themselves. Rubies are also sent to different planets to seek out specific Gems. As Rubies are merely common soldiers they are not very intelligent, having been easily fooled by Steven's claims that Jasper was on Neptune and Amethyst's obvious disguise as Jasper and according to Holly Blue Agate are seen as being incompetent or irresponsible. In the Steven Universe Podcast, Rebecca says the Rubies' main strength on Homeworld is their ability to combine; a Ruby would never be sent alone to do anything. Rubies are not supposed to have different personalities; the fact that they do "flies under the radar" because they act serious around higher-ranking Gems.
- Ruby - A Ruby that remains fused with Sapphire as Garnet, a current member of the Crystal Gems.
- Ruby (right shoulder gem) & Ruby (right back-hand gem) - Two known Rubies that used to protect Sapphire as shown in "The Answer".
- Ruby-1F4 Cut-4ND ("Eyeball") - A known Ruby sent to retrieve Jasper, another veteran of the Gem war on Earth; a witness who testified against Steven in his trial.
- "Army" - A known Ruby sent to retrieve Jasper.
- "Navy" - A known Ruby sent to retrieve Jasper, who would later steal the Roaming Eye after deceiving the Crystal Gems.
- "Leggy" - A known Ruby sent to retrieve Jasper.
- "Doc" - A known Ruby sent to retrieve Jasper and the leader of the "Ruby Squad".
- Rhodonite's unknown component Ruby - A Ruby who used to work for a Morganite before being replaced.
- Homeworld Rubies - Various Rubies who attended the "Era 3 Ball".
Not much is known about Rutiles, though they seem to have piloting capabilities.
- Rutile Twins - A Rutile whose gemstone incubated incorrectly and formed with two upper bodies with separate personalities.
- Other Rutiles - The Rutiles that ran away after the Rutile Twins emerged.
Pearls are a servant caste, described by Peridot as being "someone's shiny toy." They are expected only to serve and be submissive and obedient, simply waiting on their owners and not acting independently in any way. Pearls typically fulfill tasks such as holding their owners' belongings and serving as footpeople opening doors for their masters; they are expected to consistently exhibit subservience by remaining silent unless spoken to and remaining a few paces behind their superior when walking with them. There are exceptions to these rules depending on who the Pearls belong to, such as those of the Diamonds. Yellow Pearl is able to get away with talking down to gems higher in the caste system whenever she feels they would disturb Yellow Diamond, and clearly relishes the opportunity to do so. White Pearl is apparently seen (and feared) as an extension of White Diamond's will, making even the other Diamonds tread lightly in her presence.
Pearls also provide simple luxuries like singing, dancing and visual entertainment by projecting holograms. They are also status symbols on Homeworld reserved for higher castes such as the Diamonds and aristocrats like Sapphires, as Peridot comments that the idea of a Peridot owning a Pearl is ridiculous. Pearls may also be earned by committing a significant act of heroism. Physically, all Pearls appear to have a slender form and beak-like nose. They can also be "customized" by owners in color and appearance. Pearls are normally dismissed with the phrase "That will be all" generally followed by the owner clapping her hands twice when they are no longer needed.
- Pearl - A renegade Pearl and the sole confidant of Pink Diamond, later known as Rose Quartz. She is a current member of the Crystal Gems.
- Blue Pearl - A Pearl that serves Blue Diamond.
- Yellow Pearl - A Pearl that serves Yellow Diamond, acting as her receptionist and screening calls for her.
- White Pearl - A Pearl that serves White Diamond. She once served Pink Diamond and was known as "Pink Pearl".
- Rhodonite's unknown component Pearl - A Pearl who used to belong to and serve a Morganite before being replaced.
Pebbles act as servants in Homeworld's Caste System. They have building and sewing skills that are enough to fulfill their different tasks.
- Pink Diamond's Pebbles - A group of Pebbles that were created by Pink Diamond. They reside inside the walls and floor of Pink Diamond's palace.
Identified Gems that lack a known Gem type or role.
- Desert Glass - A corrupted Gem with the ability to create structures out of sand. She is currently bubbled in the Burning Room.
- Watermelon Tourmaline - A corrupted Gem with the ability to create strong gales with her breath. She is currently bubbled in the Burning Room.
- "Snowflake" - A former Crystal Gem mentioned by Bismuth in "Bismuth". She may be a Snowflake Obsidian, which is a type of volcanic glass.
- Larimar - A corrupted former Crystal Gem mentioned by Bismuth in "Made of Honor" nicknamed "Little Larimar" and currently bubbled in the Burning Room.
- Beryl - A corrupted former Crystal Gem mentioned by Bismuth in "Made of Honor" currently bubbled in the Burning Room. Since aquamarine, emerald and morganite are types of beryl in real life, Beryl may have had a high ranking in Homeworld society.
- Serpentine - A corrupted former Crystal Gem mentioned by Bismuth in "Made of Honor" currently bubbled in the Burning Room.
- Pyrite - In "Familiar", Blue Diamond mentioned that she let Pink Diamond name a batch of Pyrite as "Fool's Gold".
- Comby - A Gem who acts as Blue Diamond's comb due to her unusual body shape.
- Main article: Fusion Gems
Fusions (or specifically Same-Gem Fusions) are used as weapons in the caste system. They are used in times of war and solely for combat, seen as objects rather than their own beings. A fusion outside of battle is considered highly inappropriate and extremely unorthodox, being regarded as disgusting, embarrassing or discomforting to behold (as inferred from Jasper and Peridot's reactions towards Garnet). However, the existence of Topaz reveals that despite Peridot and Jasper's prejudices fusion outside of battle is indeed legal on Homeworld providing the fusion itself is same-Gem and may only be allowed for certain Gem castes (e.g. soldiers).
To a further extent, only fusions of the same type are seen as acceptable (such as a fusion consisting of several Rubies or Topazes). Fusions between Gems of different varieties are considered more of an abnormality in Gem society as the Gem diplomats of Blue Diamond's court in "The Answer" referred to Garnet's fusion with words such as "disgusting" and "unheard of". As other examples Rhodonite and Fluorite, two "off-color" fusions of different Gem types were cast out from Homeworld's society and forced to hide to avoid being shattered. Rhodonite's components were replaced by her commanding Morganite after she found out they liked to fuse. The reasoning for prejudice against Different-Gem Fusions is because they create an entirely new Gem which disrupts Homeworld's system; the new Gem has no place in the caste system and thus holds no job that will benefit the Diamonds' empire.
Gems that are defective (also referred to as "off-color") serve no use to the Gem empire and are cast out from society. If caught, these Gems are shattered. The only known exceptions to this are the Quartz soldiers stationed at Pink Diamond's Zoo who were kept in service by Blue Diamond due to previously belonging to Pink Diamond. Amethyst was another exception, being allowed to attend the Era 3 Ball providing she wore limb enhances to reach her "height requirement".
Corrupted Gems, also known as Gem Monsters are Gems who have become "corrupted", assuming a monstrous form. One of the main objectives of the Crystal Gems (other than their protection of humanity) is to defeat and contain the Corrupted Gems and hopefully cure them. These types of Gems do not exist on Homeworld and as such have no place in Gem society.