Caste System

"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!"

The Gem Homeworld once maintained 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 deviated from this, be it intentional or not would be considered defective. Since penalties for such actions were so severe most disgruntled Homeworld Gems either kept dissensions to themselves or went into hiding. Because there were so many of one type all Gems — except Diamonds — distinguished themselves via coded serial numbers. The caste system was divided up under the rule of each Diamond. If a Gem were to greet or refer to another in a higher section of the Caste System they would normally preface their Gem name with "My" to show they were their superior(s) (i.e. "My Diamond", "My Hessonite", etc).

As of the time between "Change Your Mind" and Steven Universe: The Movie, both it and the Empire had been officially dismantled.

Diamonds
Diamonds were the highest-ranked caste similar to royalty and referred to as the matriarchs of Gem society; they still made up the Great Diamond Authority. All Diamonds were (mostly) massive in size, towering over other types of Gems and even most Fusions seen. They all had diamond-shaped pupils in their eyes.

Almost all Homeworld Gems were fanatically loyal to the Diamonds; they also appeared to be categorized under their respective Diamonds as Blue Diamond once referred to Sapphire as being "of [her] court" and Peridot 5XG said she was "made for" Yellow Diamond. Infidelity displayed towards the Diamonds was considered punishable by death at the worst. Their honorific was "My Diamond".

There appeared to be rankings 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 the other Diamonds and had to obey their orders.

Beryls
While the specific roles of Beryls were not showcased the only caste members seen so far were either high-ranking Gems in charge of low-ranking Gems or diplomats of some sort. Known subtypes included Emeralds, Morganites and Aquamarines.


 * Beryl - A formerly-corrupted Crystal Gem mentioned by Bismuth.

Emeralds
Emeralds were among the high-ranking Gems. In The Steven Universe Podcast Rebecca Sugar and Ian Jones-Quartey emphasized that Emeralds (specifically the one seen in "Lars of the Stars") were elite Gems in charge of fleets. The only known Emerald had three ships (her personal shuttle, the Sun Incinerator and Destiny Destroyer) and was in charge of an unspecified amount of Gems.


 * Emerald - An Emerald whose primary craft was stolen by Lars Barriga and the Off Colors, who she continued following ever since in her imperial warship to reclaim her most prized possession from them.

Morganites
While the exact roles of Morganites remained unknown they were high enough to have their own personal Pearls and Ruby guards similar to Gems above them.


 * Morganite Commander - A Morganite mentioned by Rhodonite as having replaced her components after discovering they had fused.

Aquamarines
According to Pearl (as well as one of their members' own gloating) Aquamarines had a high rank in Homeworld's hierarchy. They appeared to serve as assistants to Diamonds, using their own ships to travel from planet to planet and collect things they wanted. Rebecca Sugar said Aquamarines were one of the high-ranked blue Gems on Homeworld.

Sapphires
Sapphires were of the nobility class, described as rare Gem aristocrats and part of the elites; in spite of this they had no immunity from outcast status. They could see imminent events using their "future vision". Sapphires were the only normal Gems with this ability. Their honorific was "Your Clarity".

Padparadschas
Padparadschas were a subtype of Sapphires equal in ranking. However, the only one seen could have visions of events in the past just a few moments after they happened.

Garnet mentioned Padparadschas were a rare kind of Gem in "Your Mother and Mine".

Garnets
While the exact roles of Garnets were unknown they seemed to be high-ranking as the only true caste member seen was in charge of lower-ranking Gems. Subtypes of Garnets included Hessonites, Demantoids and Pyropes as mentioned by Blue Diamond in "Together Alone". The Fusion Garnet apparently had no relation despite sharing a name as Blue Diamond was surprised to hear that she called herself one.

Hessonites
While the exact roles of Hessonites were still unknown they appeared to be commanders. The only one seen was the Corrupted Gem Nephrite's ex-leader. She issued her and her crew the order to travel to Earth and later retreat from the incoming Diamond attack. She would return in Save the Light (marking her official debut in the series canon). Like the one mentioned some Hessonites were 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 at least from the colonization of Earth until the end of the war. She traveled back to Earth in order to retrieve the Prism after losing it during a fight with Rose Quartz, once again encountering the other Crystal Gems.

Demantoids
Demantoids were a subtype of Garnets mentioned by Blue Diamond.

Pyropes
Pyropes were another subtype of Garnets mentioned by Blue Diamond.

Lapis Lazulis
Lapis Lazulis were extremely valuable to the Gem Empire. As stated by Yellow Diamond it was known that Lapis Lazulis were made for terraforming. Peridot also said they were typically partial to water and flying. Their use for terraforming planets likely explained one's ability to manipulate bodies of water with ease (and possibly enjoying farming).


 * Lapis Lazuli - A Lapis Lazuli who was trapped in a mirror for thousands of years and used by Homeworld for its invasion of Earth. She was freed by Steven Universe and eventually joined the Crystal Gems.

Jades
While their exact roles had not been shown Jades appeared to be high in the Caste System given they attended the Era-3 Ball. Unlike most Gems Jades had distinctive differences between their physical appearances depending on which type of Jade they were.

Nephrites
Nephrites were a subtype of Jades in charge of piloting Homeworld Dropships to begin colonizations and served as pilots for various other spaceships; they would also start building on colonies. Their ranking was never clearly stated but appeared to be high considering they captained their own ships and Yellow Diamond was shown to contact one directly in "Jungle Moon", something she would not do with lower-ranking Gems. Numerous Nephrites were 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.

Topazes
Topazes seemed to be soldiers, obeying orders and acting as bodyguards for assigned Gems; these were traits shared with Quartzes and Rubies. A fusion of two was sent to Earth by the Diamonds alongside Aquamarine to find human beings to put in Pink Diamond's human zoo. These Topazes were efficient at trapping and engulfing others within their fusion-form. Topazes also acted as guards of places suitable for more elite Gems as seen in "Familiar". Rebecca Sugar said Topazes were high-ranking yellow Gems.

Spinels
Spinels were made to be entertainers, providing entertainment for those designated as their "best friend". They were implied to be somewhat rare as Pearl stated that Steven was "a lucky one" for acquiring such a Gem. The body of the only one seen was more elastic than that of any other Gems, even going beyond the movements of Bismuth. According to Rebecca Sugar, Spinels are shaped like playing card suits (hearts, clubs, spades).


 * Spinel - The main antagonist of the movie who was close to Pink Diamond before being given Earth; she played a game with Pink by waiting at her garden for her to come back which lasted for 6,000 years until Steven brought down the Caste System and Empire. Upon realizing the true purpose of Pink Diamond's "game" she furiously traveled to her former friend's colony armed with a modified Injector and Gem Rejuvenator to destroy both the planet and her son. She eventually gave up and went back to Homeworld with the other Diamonds.

Zircons
Zircons acted as lawyers for the courts of Homeworld. They had no choice over what cases they prosecuted or defended for as revealed in "The Trial" and were assigned them instead. In the podcast Rebecca Sugar and Ian Jones-Quartey said they had a sort of medium rank, serving the upper classes but having no individual power.


 * Blue Zircon - A Zircon who defended Steven during his trial.
 * Yellow Zircon - A Zircon who acted as the prosecutor during Steven's trial.

Peridots
Peridots served mainly as technicians and Kindergarteners, sometimes performing field assignments on other planets such as the Peridot who befriended Steven and joined the Crystal Gems. Being workers Peridots had a low rank, only being allowed into elite Homeworld areas if a job was needed to be done there.

Era-2 Peridots were given Limb Enhancers to compensate for the lack of strength and unique abilities older Gems had due to the depletion of resources on Homeworld. One Peridot so far was shown to have ferrokinetic abilities.


 * Peridot Facet-2F5L Cut-5XG – A former Yellow Diamond court member assigned to report on the status of Earth and now part of the Crystal Gems.
 * "Squaridot" - A subordinate of Hessonite nicknamed for her hair. She is currently bubbled.

Quartzes
Quartzes, like Topazes and Rubies were a soldier caste. Made to fit the roles of elite warriors, Quartzes normally had incredible height, broad shoulders and an intimidating muscular build. Rose Quartz and Jasper both fit this description; Amethyst was also a Quartz although she did not fit the description because she "stayed in the ground too long" and was therefore "overcooked". Some Quartzes were used as bodyguards and escorts as shown in Jasper's case. They appeared to be less numerous than Rubies though greater than Topazes. According to Ian Jones-Quartey some had defensive powers as well (like Rose Quartz) since "they [couldn't] all be tanks". Quartzes were described as being "huge, loyal soldiers". Jasper stated Quartzes were made to fight and her kind specifically always got what they wanted. Some also acted as semi-elite guards at Homeworld outposts such as Pink Diamond's Zoo or like the Quartzes commanded by Emerald and Hessonite. They were Gems commonly made on Earth. Quartzes were the most diverse known Gem-type including Agates, Amethysts, Carnelians, Citrines, Jaspers and Rose Quartzes.

Agates
Agates were Quartzes that seemed to have a higher ranking than standard made-for-battle ones with roles as administrators. Yellow Diamond stated in "What's the Use of Feeling (Blue)?" that they were meant to be terrifying figures intimidating Gems under them into obedience. In "The Trial" it was revealed they could also be bodyguards for Gems such as Diamonds. It could be assumed that based on the way Holly Blue Agate acted around Sapphire that Agates, while having some authority were not very high-ranking Gems or at least not when compared to Sapphires.

Citrines
Citrines were a subtype of Quartzes who seemed to be elite guards serving high-ranking Gems.

Rose Quartzes
Rose Quartzes were new compared to other Gems, having been created on Earth. Sometime between the start of one Rose Quartz's rebellion and Pink Diamond's shattering every Rose Quartz in existence was bubbled. They resided in Pink Diamond's Chamber in her Zoo. It was stated in "That Will Be All" that Blue Diamond wished to keep the Rose Quartzes around for the sake of preserving Pink Diamond's legacy while Yellow Diamond wanted them to be shattered as they believed one to be responsible for the start of the Rebellion and Pink Diamond's destruction, although this was not really the case. While still being soldiers Rose Quartzes were apparently known for defensive powers rather than the offensive abilities other Quartzes had.

Amethysts
Amethysts were a subtype of Quartzes with purple coloring. The Prime Kindergarten on Earth produced Gems of this type. Amethysts acted as soldiers or guards as seen with the Amethysts guarding Pink Diamond's zoo.

Carnelians
Carnelians were a subtype of Quartzes with maroon-red coloring. The Beta Kindergarten on Earth produced Gems of this type. Based on Amethysts it could be presumed they would be Gems of the soldier type as well.

Jaspers
Jaspers were a subtype of Quartzes mostly shown to have tangerine skin and red-orange markings though some were different colors, shapes and sizes depending on the kind of Jasper they were. Similar to other Quartzes below Agates they acted as either soldiers or guards.

Tiger's Eyes
Tiger's Eyes were a subtype of Quartzes yet to be seen but mentioned by name.

Others
Other Quartzes lacking specific gemstone identifications.

Bismuths
Bismuths were builders for aristocratic members of Gem society. As such they possessed 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 was poofed and bubbled by Rose Quartz and later Steven when she developed a weapon devised to shatter Pink Diamond, unaware Rose and Pink were one and the same. She permanently rejoined the team after "Made of Honor".

Rubies
Rubies were another soldier caste and nearly the lowest-ranked of all Gems. They also filled the roles of personal escorts and bodyguards as well, even acting as scouts on recovery missions. Due to their numbers individual Rubies were considered expendable footsoldiers or cannon fodder and much of their worth in Homeworld's armies came from fusing with each other.

Rubies had almost no differences in appearance and were not supposed to have different personalities; the fact that they did "[flew] under the radar" because they mostly acted serious around higher-ranking Gems.

Pearls
Pearls were a servant caste and had such a low rank they weren't even considered real Gems, instead being viewed as property. They were 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 provided simple luxuries like singing, dancing and visual entertainment by projecting holograms.

Unlike other Gems Pearls did not have a set uniform as they could be customized in colors and appearances. The position of a Pearl's gemstone was made to match that of their owners.

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.

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.

Unknown Roles/Gem-Types
Gems lacking known Gem-types and/or societal roles.
 * Desert Glass - A formerly-corrupted Gem first seen in "Steven's Lion" with the ability to create structures out of sand currently bubbled.
 * Watermelon Tourmalines - Not much was known about these Gems.
 * Watermelon Tourmaline - A formerly-corrupted Gem with the ability to create strong gales through breathing first seen in "Beach Party". She was uncorrupted in "Change Your Mind" and last seen at Rose's Fountain.
 * Other Watermelon Tourmaline - A formerly-corrupted Gem and possible Fusion who resides in Little Homeworld.
 * 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.
 * Rutile Twins - A Rutile whose gemstone incubated incorrectly and formed two upper bodies with separate personalities.
 * Other Rutiles - Rutiles that ran away after the Rutile Twins emerged.
 * Larimar - A formerly-corrupted Crystal Gem mentioned by Bismuth nicknamed "Little Larimar".
 * Serpentine - A formerly-corrupted Crystal Gem mentioned by Bismuth currently bubbled.
 * Pyrites - In "Familiar" Blue Diamond mentioned she let Pink Diamond name a batch of Pyrites as "Fool's Gold".
 * Comby - A Gem in the shape of a hairbrush who served Blue Diamond.
 * Kyanites - In "Familiar" Blue Diamond mentioned she let Pink Diamond bring alien worms to Homeworld from a colony of Kyanites.

Defective Gems
Defective Gems, also referred to as being Off-Color served no use to the Empire and were cast out of its society. If caught these Gems were shattered. The only exceptions were the Quartzes stationed at Pink Diamond's Zoo kept in service by Blue Diamond. Amethyst was another exception, allowed to attend the Era-3 Ball provided she wore Limb Enhancers like Era-2 Peridots to reach her "height requirement".

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.

Mutant/Cluster Gems
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.

Trivia

 * 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.