Gems

Gems are an extraterrestrial species of "magical", roughly humanoid beings. 5,750 years ago, the Gem Homeworld maintained several outposts on Earth, with plans to completely colonize the planet, but were driven off by Rose Quartz's rebellion, leaving only a few Gems as the only remaining Gems on the planet.

Appearance
Gems tend to appear human-like in appearance (some more so than others) and come in a wide array of colors, appearances, sizes, and structures based on their gemstone type. While most Gems seen have two eyes, some Gems or types of Gems only have one eye (e.g. Nephrites, Sapphires, Bixbite, etc.). Their bodies seem to be made up of doll-joint-like segments in their base forms (although this isn't always apparent), and they lack features such as breast forms, nipples, or navels, due to the fact that they do not naturally possess reproductive systems (although they can shapeshift such features). It is unclear whether or not Gems generally have human-like external ears, as the same Gems have been drawn both with and without them in different shots. However, all known Gems have hair or visors that normally cover where their ears would be, and Topaz can hear despite having gemstones in place of both her ears, suggesting that Gems do not need human-like ears to hear - and, as above, they can shapeshift ears if they need them.

Description
Gems are characterized by the gemstone embedded somewhere on their body, which is analogous to a brain. However, the gem is the only true part of a Gem’s body, the only part that is unchanging and, indeed, the only part of a Gem that can be permanently damaged or killed.

Gems' humanoid shapes are projections from their gemstone which can be changed at will, described as being "like a hologram, but with mass," with their only constant feature being their gemstone and color scheme (shapeshifting is generally not permanent, and Gems will return to their "default" form eventually, unless the shapeshifting was done during regeneration). As such, Gems cannot change the size or shape of their gem, which is the limiter of how small a given Gem can be. Gems refer to their physical bodies as 'Illusions.' Gems' physical forms typically have characteristics associated with human femininity, but all Gems are sexless and genderless, the only exceptions being Human-Gem Hybrids.

Gems get their energy by absorbing light from their surroundings. Rebecca Sugar once described them as "solar-powered robots".

There are a variety of gemstones, which decides a Gem’s basic abilities, general appearance, skills and personality (though Gems are fully capable of growing beyond the functions they were designed with). There are multiple Gems with the same gemstone except for the Diamonds, of which all four are unique. The gemstone of a Gem is what decides their name. The gemstone can be located in many different parts of the body, regardless of Gem.

Typical Gem abilities include inhuman physical strength and durability of varying degrees, weapon-summoning, fusion, the power to store material in a pocket dimension within their gemstones, the ability to use their gemstones like a flashlight, and bubble creation. Note that these are not ubiquitous; some Gems, such as Lapis Lazuli, are not able to summon a personal weapon, and Gems created in sub-optimal conditions, such as second era Peridots, lack the same physical strength as other Gems. So far, all Gems with their own weapons have the ability to direct energy through their weapons, such as Garnet using her gauntlets to charge Greg's van, Pearl firing an energy blast from the tip of her spear and Amethyst sending bursts of energy through her whips.

Gems are engineered to adapt to a variety of conditions and cannot die by natural causes, as their bodies are only projections of light. Gems do not have to breathe, eat, drink, or sleep to survive, and they do not age, making them effectively immortal. They can, however, still eat and sleep if they so desire. Their bodies will also automatically alter themselves to fit the conditions of whatever celestial body or spacecraft they are on, such as adjusting mass for gravity. The only way to destroy or "kill" a Gem is to destroy their gemstone. However, a shattered gemstone can be put back together. This has been shown in Fragments and Homeworld Bound, when Steven repaired Jasper after he inadvertently shattered her, and Yellow Diamond repaired gems who were part of her cluster experiments. They still retain cracks on their gems, and to cure their effects they need to be healed. When the physical body of a Gem is seriously injured, they will retreat into their gemstone to regenerate. This is one of the only times Gems can make permanent changes to their physical form. The length of the regeneration process can range from minutes to weeks, but a "rushed" regeneration can suffer from physical deformities. Regeneration can be prevented if a gemstone is bubbled or otherwise constricted, such as within a mirror.

If a Gem's gemstone is damaged, their physical form will deteriorate and render them incoherent as the gemstone is the true body of the Gem. The only known method of healing a physically damaged Gemstone are the powers of the Diamonds and Rose Quartz. A Gem's gemstone can be used as an energy source, even if damaged. Gem Shards, the remnants of a shattered gemstone, possess a "powerful partial consciousness" which can grant sentience to their containers and have been used to create drone soldiers. Gem Shards have also been forced to fuse together over time to form Cluster Gems.

If a Gems physical form receives sufficient physical damage or is otherwise disrupted it "poofs", turning into a cloud of mist and leaving the gemstone behind, the only permenant forms of damage for Gems are cracking, shattering and corruption. Shattered gems are not dead, but their mind is splintered between the pieces, unable to properly think. Gems that have been corrupted are not damaged physically, but have been afflicted with a corruption that prevents them from thinking or understanding. Because a Gem must actively create their physical form, when a corrupted Gem reforms it instead becomes a monstrous and deformed creature called a Gem Monster, while a damaged Gem will retain their original form, albeit with some slight differences. Shattered Gems will attempt to reform, usually resulting in unintelligent limbs.

Culture

 * There are two known main groups of Gems: Homeworld Gems and the Crystal Gems.
 * Homeworld society is ruled by the autocratic Great Diamond Authority. Its members impose a strict caste system based on the gemstone and maintain their empire by terraforming worlds (and destroying them in the process) through facilities like the Kindergarten. Homeworld society heavily stigmatizes fusion between Gems of different gemstones, and fusion between Gems of the same gemstone is reserved solely for combat (and missions requiring the force of more than one Gem, in the case of Topaz).
 * The Crystal Gems are a rebellious group of Gems established by Rose Quartz who disagree with the customs and principles of Homeworld society, particularly on its perspective toward life. Five thousand years ago, Rose instigated the Rebellion against the Homeworld Gems to protect the Earth. The Crystal Gems were able to successfully drive the Homeworld Gems off-planet. As they withdrew, the Diamonds released a powerful attack, corrupting the majority of the remaining Gems on Earth. Rose, Garnet, Pearl, and Bismuth were the only Crystal Gems to survive.
 * Gem culture is ancient, predating all known human civilizations.


 * Gems have their own written language, which is inscribed on many of their temples, as first seen in Steven's Room in the Pilot, despite every non-Corrupted Gem speaking "English". This may mean that they write in an English-like script, or that written words are in a (moderately) traditional Gem language.
 * Remains of Gem architecture can be seen scattered across the Earth in the form of the structures, such as the Lunar Sea Spire, the Communication Hub, and the Galaxy Warp.
 * Gem civilization is incredibly advanced, capable of creating spaceships, pocket dimensions, and teleporters.
 * Slower than light travel is now considered outdated due to the advent of teleporters. Current Gem technology is described as incomprehensible by Lapis Lazuli.
 * Individuality is not highly valued among Gems. As implied in "Bismuth", this is in part a conviction the Gem elite has forced down upon lesser Gems to limit their potential. While each Gem may exhibit their own unique nuances in personality, they all primarily adhere to the fundamental behavior and preferences of their caste and types. Whatever the case might be, like organic beings, Gems are able to define their own identities and develop unique personalities of their own. The most prime examples of this are the members of the Crystal Gems.
 * Most Gems hold little value for the preciousness of life. Being part of a society where many individuals share the same traits, Gems have come to objectify any life form, organic or Gem. As such, they tend to treat each other and themselves as disposable commodities.
 * Ian and Rebecca stated[citation needed] that this mindset comes from Homeworld propaganda where Gems like Peridot are proud because they know their place, as they think that Homeworld philosophy is the best for everyone; as part of a Gem's indoctrination, they don't question the system because they work within it, going to a bunch of different places and learning about them. They also unknowingly absorb revised history created to edit out what made Homeworld look unsuccessful or imperfect.
 * While there has never been mention of Gems practicing any form of spiritualism or religion, the existence of the Moon Goddess Statue, along with the Sea Shrine and the Pyramid Temple, implies some sort of belief system.
 * According to Emerald, Gems engage in jubilee celebrations.
 * Gem culture does not have a gender binary or a concept of gender.
 * Gems refer to each other using she/her pronouns but have no particular reason for doing so beyond arbitrary convenience.
 * The gendered term "mother" is also applied often to the Gem named Rose Quartz (who gave up her physical form to create Steven Universe), by Gems, humans, and Steven Universe who is half-human and half-Gem.
 * Peridot uses the term "matriarch" when referring to the Great Diamond Authority in "It Could've Been Great".
 * Amethyst refers to Jasper as "sis".
 * It is initially difficult for Gems to comprehend human social customs such as marriage, parents, childhoods, birthdays, or funerals (as particularly evidenced in "Gem Harvest"). Given that Gems do not have a gender binary, and they reproduce by growing new Gems in Kindergartens, they apparently do not form romantic/social bonds comparable to marriage (Garnet's status as a "perma-fusion" is highly irregular). Rose herself admitted that for a long time she did not understand that infant and adult humans are the same species: Gems are created fully formed and with adult-level knowledge, so they do not have a concept of a childhood stage of growing.

Abilities
Most, if not all, Gems share the following abilities and traits:


 * Enhanced Condition: Gems can have greater strength, speed, and durability than humans. They can jump longer and higher than even the most athletic humans. The amount varies depending on the Gem type and production quality of the individual Gem - Peridot, a cheaply produced technician, is tough but physically weak, while Jasper, an "ultimate" soldier, can lift an Injector and survive a Gem Warship's explosion.
 * Non-Senescence: Gems do not age or catch physical diseases, and thus do not die of natural causes like humans. However, they can still be killed if their gemstone is shattered, and they are susceptible to mental illness.
 * Bubbling: Gems have the ability to encase an object inside a bubble. The color of the bubble depends on the Gem. The bubbles can be sent to wherever their creator considers "home". If a Gem is inside, it is kept in a form of stasis. These bubbles are entirely independent of their creator's state and seem to be able to exist indefinitely if undisturbed (The various bubbled Corrupted Gems in the Temple have remained stable regardless of the instances when the Crystal Gems have been poofed, and bubbles created by Rose Quartz, such as the bubble which contained Bismuth's gem, continue to exist even after she had become a part of Steven).
 * Shapeshifting: Gems can temporarily alter their physical forms. The more mass the altered form has relative to the Gem's normal form, the harder it is to maintain. Sufficiently skilled Gems can shapeshift into forms with additional functions, such as Amethyst shapeshifting into a working helicopter in "Message Received". Gems produced with fewer resources during the Gem Homeworld's Era 2 appear to lack this ability. As revealed in "A Single Pale Rose", Gems can't alter their coloration but they can change the rotation of their gemstone.
 * Regeneration: When a Gem suffers a fatal injury, they "poof," releasing their physical form and retreating into their gemstone in order to create a new, undamaged form. The amount of time this process takes depends on a number of factors, including whether or not they are changing the appearance of their form. As demonstrated by Amethyst in "Reformed", it is possible for a Gem to rush their regeneration process, but doing so may lead to a number of problems, such as deformed body parts. Regeneration time can range from several seconds, as shown in "Reformed", to a few weeks, such as in Pearl's case in "Steven the Sword Fighter".
 * Gravity Shifting: As stated by Peridot in "It Could've Been Great", Gems' bodies will automatically adjust to different levels of gravity. This is further elaborated on in "Adventures in Light Distortion" where Pearl says that their forms are dependent on the local gravity and air pressure.
 * Weapon-Summoning: Most Gems can summon a tangible weapon from their gemstones. Gems can summon multiple weapons at once, but each non-fusion Gem has only one type of weapon that they can summon.
 * Fusion: Gems can combine their bodies and minds to form a larger and more powerful Gem with all of their components' gemstones on their bodies. Fusion Gems can unfuse willingly or fall apart for a number of reasons, and they can fuse further without unfusing first. Fusions inherit all of their components' weapons, and may combine multiple weapons into new forms - for instance, Opal can combine Pearl's spear and Amethyst's whip to form a bow. Humans can also fuse with half-Gems, as demonstrated in "Alone Together".
 * Gem Storage: Gems can store and withdraw objects from their Gemstones.
 * Photokinesis: Gems can project light from their Gemstones to light up dark places.
 * Unique Abilities: Gems have a wide range of abilities that are exclusive to certain Gem types or individual Gems. These include Rubies' pyrokinetic touch, Sapphires' future vision, Pink Diamond/Rose's healing tears, and Peridot's magnetokinesis.

Gemstone Types
The Gem Homeworld maintains a strict caste system based on the gemstone, with each Gem belonging to a larger "type".

Reproduction
Rebecca Sugar has confirmed that Gems do not naturally reproduce and lack reproductive organs by default.

In the short "How Are Gems Made?", it is explained that Gems "aren't born, they are made when some Gems from outer space came here with these big machines! They put the machines on Earth and shot this junk into the ground, and then boom, you pop right out!" In addition, it is revealed that Gems are formed fully developed: "being a weak baby would be a pain, so, they suck up all the good stuff from the ground so we pop out all big and strong." However, this process is not entirely flawless; as put by Peridot in "Too Far", if a Gem is incubated for too long (referred as being "overcooked" by Jasper in "The Return"), it will result in the Gem's humanoid form being inherently abnormal, as in the case of Amethyst, who is much shorter than the typical Quartz. Also, as revealed in "Too Short to Ride", if not enough resources are present during the incubation process, the resulting Gems will be underdeveloped, as in the case of Era 2 Peridots, who are shorter and lack most standard Gem abilities.

In addition to being fully developed physically, they are also fully developed mentally. When they come out of the ground, they already know all that they need to know to do their job, up to and including their initial, immediate orders. Rose Quartz explains in "Greg the Babysitter" that when a Gem is made, it is for a reason. They burst out of the ground with the knowledge of what they are supposed to be, and that is what they generally believe they will be for life.

In "On the Run", it is revealed that the Homeworld Gems invaded Earth several thousand years ago and used the Kindergarten to create new Gems using the method described in "How Are Gems Made?"; and that Amethyst is one such Gem. This process is very harmful to the environment to the point where, if it were allowed to continue, it would lead to "the destruction of all life on Earth," according to Pearl in "Marble Madness". Amethyst refers to all the Gems created through the process, herself included, as "parasites".

While biological reproduction is an alien concept to Gems, some form of it is not impossible for them; while Gems cannot reproduce with each other, they can create Gem-hybrid offspring. Through shape-shifting, they can perfectly replicate the reproductive organs of organic beings for their "human constructs" in order to have sex. Rose Quartz is the only known Gem to have done this, and her son, Steven, inherited her gemstone, without which she could not project a physical form and subsequently "died". Exact details on this are extremely scant; while Rose appeared "pregnant" with Steven, no information is ever revealed as to how Steven's chromosomes were built, or how Rose acquired or constructed an ovum.

Steven asks Peridot what is it like to be created on Homeworld in "Gem Drill". She says she does not remember anything and only had feelings. She describes it as not existing then suddenly existing.