This is what White Diamond expects of all of us...! From a thin flake of mica to the deepest, hardest stone, we all must make sacrifices for the sake of our perfect empire!
|—Yellow Diamond, "Change Your Mind"|
Prior to Era 3 the Gem Homeworld maintains a strict Caste System with all types of gemstones having predetermined roles and places in the social pyramid, each with their own privileges and ordained purposes. Gems who in any way deviate from this, be it intentional or not are considered defective. Since penalties for such actions are severe most disgruntled Homeworld Gems either keep dissensions to themselves or go into hiding. Because there are so many of each Gem-type (except Diamonds) all Gems distinguish themselves via serial numbers. The caste system is divided up under the rule of each Diamond. If Gems are to greet or refer to another in a higher section of the Caste System they normally preface their Gem name with "My" to show they are their superior(s) (i.e. "My Diamond", "My Hessonite", etc).
- 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 still make up the Great Diamond Authority. All Diamonds are (mostly) massive in size, towering over other types of Gems and even most Fusions seen. They all have diamond-shaped pupils in their eyes.
Almost all Homeworld Gems are fanatically loyal to the Diamonds; they also appear to be categorized under their respective Diamonds as Blue Diamond once refers to Sapphire as being "of [her] court" and Peridot 5XG says she is "made for" Yellow Diamond. Infidelity displayed towards the Diamonds is considered punishable by death at the worst. Their honorific is "My Diamond".
There appears to be rankings within the Diamonds themselves as White Diamond is hierarchically superior to the other Diamonds and the leader of the Authority. Conversely, Pink Diamond is below the other Diamonds and has to obey their orders.
Emeralds are high-ranking gems. In The Steven Universe Podcast Rebecca Sugar and Ian Jones-Quartey emphasize that Emeralds (specifically the one in "Lars of the Stars") are elite Gems in charge of fleets. The only known Emerald has at least three ships (her personal shuttle, the Sun Incinerator and Destiny Destroyer) and is in charge of an unspecified amount of Gems.
- Emerald - An Emerald whose primary craft is stolen by Lars Barriga and the Off Colors who she continues following ever since in her imperial warship to reclaim her most prized possession from them.
Morganites are a type of gem in Homeworld society. While their exact roles remain unknown they are high enough to have their own Pearls and Rubies.
- Morganite - A Morganite mentioned by Rhodonite as having replaced her components after discovering they had fused.
- Main article: Aquamarines
Aquamarines are another type of Gem with a high rank in Homeworld's hierarchy. They appear to serve as assistants to Diamonds, using their own ships to travel from planet to planet and collect things they want. Rebecca Sugar says Aquamarines are high-ranked blue Gems on Homeworld.
- Main article: Sapphires
Sapphires are of the nobility class, described as rare Gem aristocrats and part of the elites; in spite of this they have no immunity from outcast status. They can see imminent events using their future vision. Sapphires are the only normal Gems with this ability. Their honorific is "Your Clarity". Known subtypes include Padparadschas.
Padparadschas are a subtype of Sapphires. However, the only one seen can only have visions of events in the past just a few moments after they happen.
While the exact roles of Garnets are unknown they seem to be high-ranking as the only true caste member seen is in charge of low-ranking Gems. Subtypes include Hessonites, Demantoids and Pyropes as mentioned by Blue Diamond in "Together Alone". The Fusion Gem Garnet apparently has no relation despite sharing a name as Blue Diamond is surprised to hear that she calls herself one.
While the exact roles of Hessonites are still unknown they appear to be commanders. The only one seen is Nephrite's ex-leader. She issues her and her crew the order to travel to Earth and later retreat from the incoming Diamond attack. She returns in Save the Light marking her official debut in the series canon. Like the one mentioned some Hessonites are tall with poofy hair. Their honorific, similar to that of the Diamonds was "My Hessonite".
- Hessonite - The former superior of "Squaridot" and Nephrite and former owner of the Light Prism who commanded the latter Gem and her crew from the colonization of Earth until the end of the Rebellion. She travels back to Earth to retrieve the Prism after losing it during a fight with Rose Quartz once again encountering the Crystal Gems.
Demantoids are a subtype of Garnets mentioned by Blue Diamond.
Pyropes are another subtype of Garnets mentioned by Blue Diamond.
- Main article: Lapis Lazulis
Lapis Lazulis are extremely valuable to the Gem Empire. As stated by Yellow Diamond it is known that Lapis Lazulis are made for terraforming. Peridot 5XG also says they are typically partial to water and flying. Their use for terraforming planets likely explains one's ability to manipulate water with ease (and possibly enjoying farming).
- Main article: Jades
While their exact roles have not been shown Jades appear to be high in the Caste System given they attend the Era-3 Ball. Unlike most Gems Jades have distinctive differences between their physical appearances depending on which type of Jade they are.
- Main article: Nephrites
Nephrites are in charge of piloting Homeworld Dropships to begin colonizations and serve as pilots for various other spaceships; they also start building on colonies. Their ranking is never clearly stated but appears to be high considering they captain their own ships and Yellow Diamond contacts one directly in "Jungle Moon", something not done with lower-ranking Gems. Numerous Nephrites are corrupted with one (known to Steven as Centipeetle) formerly being a captain in charge of other Nephrites under Hessonite's command and leading a dropship that went to Earth.
- Main article: Topazes
Topazes seem to be soldiers, obeying orders and acting as bodyguards for assigned Gems; these are traits shared with Quartzes and Rubies. A fusion of two is sent to Earth by the Diamonds alongside Aquamarine to find human beings to put in Pink Diamond's Zoo. These Topazes are efficient at trapping and engulfing others within their fusion-form. Topazes also act as guards of places suitable for more elite Gems as seen in "Familiar". Rebecca Sugar says Topazes are high-ranking yellow Gems.
Zircons act as lawyers for the courts of Homeworld. They have no choice over what cases they prosecute or defend for as revealed in "The Trial" and are assigned them instead. In the podcast Rebecca Sugar and Ian Jones-Quartey say they have a sort of medium rank, serving the upper classes but 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: Peridots
Peridots serve mainly as technicians and Kindergarteners, sometimes performing field assignments on other planets such as the Peridot who befriends Steven and joins the Crystal Gems. Being workers Peridots have a low rank, only being allowed into elite Homeworld areas if a job is needed to be done there.
Era-2 Peridots are given Limb Enhancers to compensate for the lack of strength and unique abilities older Gems have due to the depletion of resources on Homeworld. One Peridot so far is shown to have ferrokinetic abilities.
- Main article: Quartzes
Quartzes, like Topazes and Rubies are soldiers. Made to fit the roles of elite warriors Quartzes normally have incredible height, broad shoulders and an intimidating muscular build. Rose Quartz and Jasper both fit this description; Amethyst does not fit the description because she "stayed in the ground too long" and is therefore "overcooked". Some Quartzes are used as bodyguards and escorts as shown in Jasper's case. They appear to be less numerous than Rubies though greater than Topazes. According to Ian Jones-Quartey some have defensive powers as well like Rose Quartz since "they can't all be tanks". Quartzes are described as being "huge, loyal soldiers". Jasper states Quartzes are made to fight and her kind specifically always gets what they want. Some also act as elite guards at Homeworld outposts such as Pink Diamond's Zoo or like the Quartzes commanded by Emerald and Hessonite. They are Gems commonly made on Earth. Quartzes are the most diverse known Gem-type with subtypes including Agates, Amethysts, Carnelians, Citrines, Jaspers and Rose Quartzes.
Agates are Quartzes that seem to have a higher ranking than standard made-for-battle ones with roles as administrators. Yellow Diamond states in "What's the Use of Feeling (Blue)?" that they are meant to be terrifying figures intimidating Gems under them into obedience. In "The Trial" it is revealed they can also be bodyguards for Gems such as Diamonds. It can be assumed that based on the way Holly Blue Agate acts around Sapphire that Agates, while having some authority are not high-ranking Gems or at least not when compared to Sapphires.
Citrines are a subtype of Quartzes who seem to be elite guards serving high-ranking Gems.
Rose Quartzes are new compared to other Gems having been created on Earth. Sometime between the start of one's rebellion and Pink Diamond's shattering every Rose Quartz in existence is bubbled. They reside in Pink Diamond's Chamber in her Zoo. It is stated in "That Will Be All" that Blue Diamond wishes to keep them around for the sake of preserving Pink Diamond's legacy while Yellow Diamond wants them shattered as they believe one to be responsible for the start of the Rebellion and Pink Diamond's destruction although this is not really the case. While still being soldiers Rose Quartzes are apparently known for defensive powers rather than the offensive abilities other Quartzes have.
Amethysts are a subtype of Quartzes with purple coloring. The Prime Kindergarten on Earth produces Gems of this type. Amethysts act as soldiers or guards as seen with the Amethysts guarding Pink Diamond's zoo.
Carnelians are a subtype of Quartzes with maroon-red coloring. The Beta Kindergarten on Earth produces Gems of this type. Based on other Quartzes it can be assumed they are Gems of the soldier type as well.
Jaspers are a subtype of Quartzes mostly shown to have tangerine skin and red-orange markings though some are different colors, shapes and sizes depending on the kind of Jasper they are. Similar to other Quartzes below Agates they act as either soldiers or guards.
Tiger's Eyes are a subtype of Quartzes yet to be seen but mentioned by name.
Other Quartzes lacking specific gemstone identifications.
Bismuths are builders for aristocratic members of Gem society. As such they possess a broad stature for intense 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 is poofed and bubbled by Rose Quartz and later Steven when she develops a weapon devised to shatter Pink Diamond, unaware Rose and Pink are one and the same. She permanently rejoins the team after "Made of Honor".
- Main article: Rubies
Rubies are another soldier caste and nearly the lowest-ranked of all Gems. They also fill the roles of personal escorts and bodyguards as well, even acting as scouts on recovery missions. Due to their numbers individual Rubies are considered expendable footsoldiers or cannon fodder and much of their worth in Homeworld's armies comes from fusing with each other.
Rubies have almost no differences in appearance and are not supposed to have different personalities; the fact that they do "flies under the radar" because they mostly act serious around higher-ranking Gems.
Spinels are entertainers for those designated their "best friend". They are implied to be rare as Pearl stated that Steven is "a lucky one" for acquiring such a Gem. The body of the only one seen is more elastic than that of any other Gems, even going beyond the movements of Bismuth. According to Rebecca Sugar they are shaped like playing card suits (hearts, clubs, spades, etc.).
- Spinel - The main antagonist of the movie who is close to Pink Diamond before being given Earth; she plays a game with Pink by waiting at her garden for 6,000 years until Steven brings down the Caste System and Empire. Upon realizing the true purpose of Pink Diamond's "game" she furiously travels to her former friend's colony armed with a modified Injector and Gem Rejuvenator to destroy both the planet and her son. She eventually gives up and goes back to Homeworld with the other Diamonds.
- Main article: Pearls
Pearls are a servant caste and have such a low rank they aren't even considered real Gems, instead being viewed as property. They are expected only to serve and be submissive and obedient, simply waiting on their owners until being told "That will be all" and not acting independently in any way. Pearls also provide simple luxuries like singing, dancing and visual entertainment by projecting holograms.
Unlike other Gems Pearls do not have a set uniform as they can be customized in colors and appearances. The position of a Pearl's gemstone is made to match that of their owners.
- Main article: Pebbles
Pebbles also acted as servants but unlike Pearls who belonged to individual Gems they appeared to serve everyone. They had building and sewing skills that were enough to fulfill different tasks at incredible speed.
- Main article: Fusion Gems
Fusions (specifically Same-Gem Fusions) were used as weapons, especially in times of war and solely for combat, seen as objects rather than their own beings. Fusions outside of battle were considered inappropriate and unorthodox, regarded as disgusting, embarrassing or discomforting to behold as inferred from Jasper and Peridot 5XG's reactions towards Garnet. However, the existence of Topaz revealed that despite their prejudices Fusions outside of battle were indeed legal on Homeworld provided the Fusions were of the Same-Gem type and could only be allowed for certain castes (e.g. soldiers).
To a further extent only Fusions of the same type were seen as acceptable such as Fusions consisting of several Rubies or Topazes. Fusions between Gems of different varieties were considered an abnormality in Gem society as the Gems of Blue Diamond's court referred to Garnet as "disgusting" and "unheard of". As other examples Rhodonite and Fluorite, two more Fusions of different Gem-types were forced to hide to avoid being shattered. Rhodonite's components were even replaced by her commanding Morganite after she found out they liked to fuse. The reasoning for prejudice against Different-Gem Fusions was because they created an entirely new Gem which disrupted Homeworld's society; the new Gem could've had no place in the Caste System and thus hold no job beneficial to Homeworld.
Gems lacking known Gem-types and/or societal roles.
- Desert Glass - A formerly-corrupted Gem seen in "Steven's Lion" with the ability to create structures out of sand.
- Watermelon Tourmalines - Not much is known about these Gems.
- Snowflake Obsidian - A formerly-corrupted Crystal Gem mentioned in "Bismuth" presumably a subtype of Obsidians and Volcanic Glasses. She was uncorrupted in "Change Your Mind" and resided in Little Homeworld.
- Rutiles - Not much is known about Rutiles though they seem to have piloting capabilities.
- Larimar - A formerly-corrupted Crystal Gem mentioned by Bismuth nicknamed "Little Larimar".
- Beryl - A formerly-corrupted Crystal Gem mentioned by Bismuth.
- Serpentine - A formerly-corrupted Crystal Gem mentioned by Bismuth.
- Pyrites - In "Familiar" Blue Diamond mentions she lets Pink Diamond name a batch of Pyrites as Fool's Gold.
- Comby - A Gem in the shape of a hairbrush who serves Blue Diamond.
- Kyanites - In "Change Your Mind" Blue Diamond mentions she lets Pink Diamond bring alien worms to Homeworld from a colony of Kyanites.
Defective Gems, also referred to as being Off-Color serve no use to the Empire and are cast out of its society. If caught these Gems are shattered. The only exceptions were the Quartzes stationed at Pink Diamond's Zoo kept in service by Blue Diamond. Amethyst is another exception, allowed to attend the Era-3 Ball provided she wears Limb Enhancers like Era-2 Peridots to reach her "height requirement".
- Main article: Corrupted Gems
Corrupted Gems, also known as Gem Monsters were Gems who became corrupted by the Diamonds after the Rebellion, assuming monstrous and nigh-incoherent forms. One of the main objectives of the Crystal Gems other than the protection of humanity and Earth was to defeat, contain and hopefully cure these Gems. They did not exist on Homeworld and as such had no place in its society.
Cluster Gems, otherwise known as Gem Mutants were originally Crystal Gems shattered into Gem Shards during the Rebellion who were fused against their will into monsters similar to Corrupted Gems. The Cluster was a result of the Diamonds attempting to harness this process to create a planet-destroying "geo-weapon" which would first destroy Earth and eventually other planets as well.
- This utilitarianism or functionalism-inspired system of judging an individual's worth based only on their generalizations was similar to the Caste System and Functionism from the Transformers franchise, specifically the Aligned series and 2005 IDW Generation One reboot.