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!"

Before Era 3, the Gem Homeworld maintained a strict Caste System with gemstones having predetermined roles/places in the social pyramid, their privileges and ordained purposes and Gems who deviated from this were considered defective. Since penalties were severe most disgruntled Homeworld Gems kept to themselves or went into hiding. Because there were so many of each Gem-type (except Diamonds) all Gems normally distinguished themselves via serial numbers. The Caste System was divided up under the rule of the Diamonds and other "Homeworld elites"; if Gems were to greet or refer to others in higher sections of the Caste System they normally prefaced their Gem name with "My" to show they were their superior(s).

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

Real-World Relations/Differences
The Caste System is somewhat tied to real-world gemology and mineralogy (i.e. Diamonds being the highest as real-life diamond is highest on the Mohs scale of mineral hardness). However, this is not a proper rule for the series as it takes creative liberties with Gem-types and their rankings including but not limited to:
 * Ruby and sapphire are varieties of corundum in the real world while Rubies and Sapphires are different and unrelated in the series. The same applied to Aquamarines, Emeralds, Bixbites, Morganites and Beryls which are all beryl in the real world but separate and different in the series. Nephrite is under jade in the real world but Nephrites and Jades seem to share no technical relations although both are voiced by Aparna Nancherla possibly as a nod to their real-world equivalents.

Diamonds
Diamonds were the highest ranking Gems similar to royalty and referred to as the matriarchs of society; they still made up the Great Diamond Authority. All Diamonds were (mostly) massive towering over other Gems and most Fusion Gems seen with diamond-shaped pupils in their eyes.

Most Homeworld Gems were fanatically loyal to them and 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 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; this relationship resembled a dysfunctional family more than a hierarchy.

Each of the Diamonds had their own aspect of the empire to govern.White Diamond created the rules that governed the empire and held complete authority over all gems,Yellow Diamond was in charge of all of homeworlds military,Blue Diamond was in charge of diplomacy and enforcing rules,and Pink Diamond hosted balls to celebrate accomplishments of the other diamonds.

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

Garnets
Garnets were commanders that aided in conquering and controlling planets; in some cases they were Light Prism-bearers and commanded entire colonies. Certain Garnets seemed to command different types of Gems but it is unknown if this specifically applied or not. Subtypes included Hessonites, Demantoids and Pyropes.

The Fusion Gem of the same name had no relation as Blue Diamond was surprised to hear she called herself one in "Together Alone".

Hessonites
Hessonites were a subtype of Garnets with orange colors who commanded armies for colonization or war. They oversaw Quartzes such as Citrines as well as Nephrites and were more focused on strategies and battles.

Demantoids
Demantoids were a subtype of Garnets with yellow-green colors first mentioned by Blue Diamond in "Together Alone" who served as overseers of lower classes, worked on colony infrastructures and were more focused on technology.

Pyropes
Pyropes were a subtype of Garnets with pink-red colors first mentioned by Blue Diamond in "Together Alone" who served as overseers of upper classes making up Homeworld's aristocracies once colonies were completed. Pyropes were noticeably fancier wearing dresses or gowns and living in places like the Palace of Light.

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

Morganites
Morganites were high-ranking. While their exact roles remain unknown they were high enough to have Pearls and Rubies.


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

Aquamarines
Aquamarines were another type of high-ranking Gems. 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 high-ranked blue Gems.

Lapis Lazulis
Lapis Lazulis were valuable to the Empire. As stated by Yellow Diamond in "What's the Use of Feeling (Blue)?" they were made for terraforming and as such able to manipulate large quantities of water and utilize it in almost any way imaginable like slicing even through solid rock and reshaping planets with ease; this was likely how the canyons for Kindergartens were created.

Jades
Jades appeared to be high-ranking given they attended the Era 3 Ball. Unlike most Gems they had differences between their physical appearances depending on which type of Jade they were and had been seen in different subtypes.

Topazes
Topazes seemed to be soldiers obeying orders and acting as bodyguards for assigned Gems; these were traits shared with Quartzes and Rubies. 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.

Nephrites
Nephrites were in charge of piloting spaceships and helping build colonies. Their ranking was never clearly stated but appeared to be high considering they captained their own ships and Yellow Diamond contacted one directly in "Jungle Moon" which she would not do with low-ranking Gems. One Nephrite was a captain in charge of other Nephrites under Hessonite's command and leading a dropship that went to Earth.

Zircons
Zircons acted as lawyers though 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 no individual power.

Quartzes
Quartzes, like Topazes and Rubies were soldiers. Made to fit the roles of elite warriors Quartzes normally had incredible height, broad shoulders and an intimidating muscular build. Jasper fit this description but Amethyst did not because she "stayed in the ground too long" and was therefore "overcooked". Some were used as bodyguards and escorts as shown in Jasper's case. They appeared to be less numerous than Rubies through greater than Topazes. According to Ian Jones-Quartey some had defensive powers as well like Rose Quartz since "they can'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 elite guards at Homeworld outposts such as Pink Diamond's Zoo or like the Quartzes commanded by Emerald and Hessonite. They were Gems common on Earth and the most diverse known Gem-type with subtypes including Agates, Amethysts, Carnelians, Citrines, Jaspers and Rose Quartzes.

Agates
Agates seemed to take on administrative roles as higher-ranking Gems. Yellow Diamond stated in "What's the Use of Feeling (Blue)?" they were meant to be terrifying figures intimidating Gems under them into obedience. In "The Trial" it was revealed they could also be bodyguards. It could be assumed based on the way Holly Blue Agate acted around Sapphire and the Diamonds that while having some authority Agates were not high-ranking compared to Sapphires.

Citrines
Citrines were a subtype of Quartzes appearing 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's rebellion and Pink Diamond's shattering every Rose Quartz in existence was bubbled and made to reside in Pink Diamond's Chamber in her Zoo. It was stated in "That Will Be All" that Blue Diamond wished to keep them around for the sake of preserving Pink Diamond's legacy while Yellow Diamond wanted them shattered as they believed one to be responsible for the start of the Rebellion and Pink Diamond's destruction although this was not the case. While still being soldiers they were known for defensive powers rather than the offensive abilities other Quartzes had although this may be exclusive to the Rose Quartz who was Pink Diamond and not the cut of Gem as a whole. Their gemstones appeared to be modeled after the table facet of Pink Diamond's gemstone lacking the pavilion and having a mirrored back.

Cherry Quartzes
Cherry Quartzes were a subtype of Quartzes with pink coloring. Based on other Quartzes it could be assumed they were soldiers as well.

Amethysts
Amethysts were a subtype of Quartzes mostly with purple coloring. The Prime Kindergarten on Earth produced Gems of this type. Amethysts acted as soldiers and/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 produces Gems of this type. Based on other Quartzes it could be assumed they were also soldiers.

Jaspers
Jaspers were a subtype of Quartzes shown to mostly 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.

Angel Aura Quartzes
Angel Aura Quartzes were a subtype of Quartzes with iridescent coloring. Based on other Quartzes it could be assumed they were soldiers as well.

Peridots
Peridots served as technicians and Kindergarteners sometimes performing field assignments on other planets such as Peridot 5XG. Being workers they had a low ranking and were only allowed into elite Homeworld areas if a job was needed to be done there.

In Era 2 Peridots and even other Gems were given Limb Enhancers to compensate for the lack of strength and unique abilities due to the depletion of resources on Homeworld. Despite this Peridot 5XG was shown to have ferrokinetic abilities.

Larimars
Larimars served as sculptors for the elites although it is unclear if this gave them a high ranking or not.

Bismuths
Bismuths were builders for aristocratic members of 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 shapeshifting to fit a wide variety of purposes.

Obsidians
Obsidians were tall Gems with a muscular upper half. Like Bismuths they were workers who dug trenches and other encampments. Certain subtypes seemingly worked in specific areas. Unlike Garnets which shared similarities regardless of being Fusion Gems or not the only one seen shared no physical characteristics with the Fusion Gem of the same base name. Known subtypes included Snowflake Obsidians.

Snowflake Obsidians
Snowflake Obsidians were a subtype of Obsidians with white markings and grey colors who used ice and snow to carve out military posts.

Rubies
Rubies were another type of soldiers and nearly the lowest-ranked Gems of all. They also filled the roles of escorts and bodyguards as well as scouts. Due to their numbers individual Rubies were considered expendable footsoldiers or cannon fodder and much of their worth came from fusing.

Rubies had almost no differences in appearance and were not supposed to have different personalities; the fact they did "flies under the radar" because they acted seriously around high-ranking Gems.

Spinels
Spinels were entertainers, playmates and court jesters. They were implied to be rare as Pearl stated in "system/BOOT.pearl final(3).Info" that Steven was a "lucky one" for acquiring such a Gem. The body of the only one seen was more elastic than other Gems even going beyond the movements of Bismuth. According to Rebecca Sugar their gemstone cuts were shaped like playing card suits (hearts, clubs, spades and diamonds).

Pearls
Pearls were servants and had such a low rank they were not even considered real Gems but 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 entertainment by projecting holograms.

Unlike other Gems Pearls did not have set uniforms as they could be customized in colors and appearances. The position of a Pearl's gemstone along with their colors was made to match their owners (except for the Crystal Gems' Pearl likely because she was Pink Diamond's replacement Pearl as opposed to her original one whose features did match her owner). Pearls could be brought to the Reef to be customized, repaired or reset if necessary.

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. They were mainly used to create funiture and decorations in living quarters at the owners command while staying out of sight inside walls. They appeared to be the lowest-ranking Gems as they were seldom acknowledged and/or thanked.

Fusion Gems
Fusion Gems, Gem Fusions or just Fusions, specifically Same-Gem Fusions were used as weapons, especially in times of war and solely for combat as objects. Fusions outside of battle were considered and regarded as inappropriate, unorthodox, 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 this Fusions outside of battle were indeed legal on Homeworld provided they were of the Same-Gem type and could only be allowed for certain caste positions (e.g. soldiers). Even then they were still looked down upon for having a capacity of sentimentality as revealed by Aquamarine.

To a further extent only fusions of the same type were seen as acceptable such as Fusions consisting of Rubies or Topazes. Fusions between Gems of different varieties were considered abnormalities as the Gems of Blue Diamond's court referred to Garnet as "disgusting" and "unheard of". As other examples Rhodonite and Fluorite were forced to hide to avoid being shattered and the former's components were even replaced by their Morganite after she found out. 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 have had no place in the Caste System and thus hold no job beneficial to Homeworld.

Gem Shards
Gem Shards or Shards were the remains of Gems shattered mostly for rebelling against the Caste System. However, according to Pearl in "Frybo" they still had "a powerful partial consciousness that has been harnessed by Gems throughout history to create semi-sentient drone soldiers with the capacity to follow basic orders"; like intact gemstones they could be used as power sources as seen in "Friend Ship". Unfortunately this proved dangerous to the point Shards in containers ended up attacking everything around them; in some cases they regenerated as disembodied limbs that would seek out the missing parts of themselves in hopes of reuniting.

Unspecified Gem-Types/Roles
Gems lacking known Gem-types and/or societal roles. These types of Gems have been seen in full but their places in the Caste System have not alluded to enough to determine their exact positions.

Bixbites
Bixbites were tall bony Gems with doll-like joints. Their ranking is unknown but it was implied their role involved being able to cut with precision. It is possible they worked in construction and manufacturing.

Rutiles
Rutiles were tall lanky Gems with a somewhat rectangular build resembling real-life rutile. Although not much was known about them they seemed to have piloting capabilities. Judging by the words of the Rutile Twins they appeared to be mass-produced thus likely holding a low rank although this is unconfirmed.

Spodumenes
Spodumenes were Gems with large singular eyes sometimes covered by hair. They have only been seen in one color although spodumene comes in many colors in the real world. Known subtypes included Orange Spodumenes.

Orange Spodumenes
Orange Spodumenes were a subtype of Spodumenes with orange colors.

Tourmalines
Tourmalines were large bulky Gems with balloon-like features.

Watermelon Tourmalines
Watermelon Tourmalines were a subtype of Tourmalines with pink and green colors.

Unnamed Green Miniature Gem-Type
This type of Gem had varying shades of green ranging from bright lime-yellow to pale forest-green. They were small in stature compared to Aquamarines and appeared to be high-ranking given they had spires to live in.

Unnamed Violet Gem-Type
Very little was known about this type of Gem. They appeared to have a hunched stout build and the only instance shown was shrouded in a gelatinous cloak revealing very little about her physical features.

Unnamed Green Gem-Type
Not much was known about this type of Gem although one had a gemstone similar to the Heaven Beetle and Earth Beetle.

Other Unknown Roles/Gem-Types

 * Desert Glass - A presumably uncorrupted Gem seen in "Steven's Lion" with the ability to create structures out of sand. Her physical form has not been seen.
 * Beryls - Nothing is known about this type of Gem although one was a Crystal Gem during the Rebellion. Despite sharing a real-world mineral class with Aquamarines, Emeralds, Bixbites and Morganites they appeared to be unrelated.
 * Serpentines - Nothing is known about this type of Gem although one was a Crystal Gem during the Rebellion.
 * Pyrites - In "Familiar" Blue Diamond mentioned she let Pink Diamond name a batch Fool's Gold. They may be high-ranking due to a small batch seemingly being regarded as a specialty.
 * Comby - A Gem in the shape of a comb who served Blue Diamond and resembled the Pebbles.
 * Sentient Walls - Presumably-harvested Gems appearing embedded in the hallway of Yellow Diamond's Extraction Chamber. Their full physical forms have not been seen.
 * Sentient Statues - More presumably-harvested Gems appearing in Blue Diamond's Extraction Chamber. Their full physical forms have not been seen.
 * Kyanites - In "Change Your Mind" Blue Diamond mentioned she let Pink Diamond bring alien worms to Homeworld from a colony of them. Although kyanite comes from quartz in real life the two appear to be unrelated.
 * "Micas" - A type of Gem mentioned by Yellow Diamond in "Change Your Mind".
 * "Chalks" - A type of Gem mentioned by Bismuth in "Change Your Mind".

Defective Gems
Defective Gems referred to as Off-Color served no use to the Empire, were cast out of its society and if caught were shattered. The only exceptions were the Quartzes at Pink Diamond's Zoo kept in service by Blue Diamond. Amethyst was another exception, provided she wore Limb Enhancers like Era 2 Gems 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 in Homeworld and as such had no place in its society.

Mutant/Cluster Gems
Cluster Gems, otherwise known as Gem Mutants were Crystal Gems shattered during the Rebellion and 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 "geo-weapon" which would destroy Earth and other planets as well.

Trivia

 * This utilitarianism or functionalism-inspired governing system of judging an individual's worth on their outward appearances were similar to the Caste System and Functionism from Transformers, specifically the Aligned series and 2005 IDW Generation One reboot in that they were glaringly suppressive, toxic, flawed and resulted in uprisings that brought about the end of times during which many lived in fear for their lives should they have stepped out of line.
 * The movie revealed that Gem Rejuvenators were the initial method of wiping out disobedient Gems but due to being able to restore their memories from something that influenced them this was ended in favor of imprisonment, harvesting and shattering.
 * Gems representing subtypes of beryl in real life were not related in the series; most Beryl-type Gems shown had high rankings although it is unknown what ranking Beryl and Bixbite's purposes gave them.