The Crystal Gems' Entire Backstory Explained

When you're writing a kids' show, it isn't necessary to create a dense world full of logical constraints and slowly revealed mysteries. Nobody asked why Dora explored, and trying to find reason in Bikini Bottom is a path to madness. Still, the crew of artists that fanned out from the Cartoon Network series Adventure Time seem to crank out richly detailed universes for their bright and colorful creations as a matter of course. The most obvious example of this comes in Rebecca Sugar's treatise on the importance of caring and love-cum-intergalactic war story, Steven Universe.

From the outside, Steven Universe appears to be a cuddly, fast-paced show about acceptance, joy and creating family wherever you find it. And it is those things. But Sugar buried a story within the very foundation of the show that touches on the ravages of war and the bond it can create between those left behind. It sounds like heady stuff, and frankly it is, but it's a big part of what makes the show so rewarding for its older cohort of viewers. As the show went on through its five seasons, a picture was slowly revealed. In the background of the story about a young boy coming to grips with his powers and his place in the world, Sugar was also telling the story of a millennia-long struggle between a small band of rebel forces and a tyrannical empire.

This is the story of the Crystal Gems.

Before we can get into how the rebel band of gems and protectors of Earth came to be, it helps a bit to know about where they are from. Steven Universe's world is populated by anthropomorphized gemstone creatures called Gems. All Gems hail from a home planet, fittingly called Homeworld, ruled over by four massive titan figures: Pink Diamond, White Diamond, Yellow Diamond and Blue Diamond.

Each Diamond was endowed with certain characteristics, ones that showed through in their underling gems. Yellow Diamond is militaristic and logical. She leads the colonizing armies and her associated Gems are engineers and warriors. Blue Diamond is an empath whose gems tend to be prescient and emotional. Pink Diamond is passionate and her underlying gems tend to be quick to anger and joy. White Diamond is a fascistic leader obsessed with ideological purity. Her Gems tend to be rule followers.

In Gem society, birth determines function. A Gem's type will tell others what they do with their life. For example, Pearls are servants and Rubies are warriors. This will become important when an eventual rebel leader decides it's time for each living Gem to decide their own destiny.

Gems propagate and expand their intergalactic empire by setting up "kindergartens" on various colonized planets. The kindergartens are massive canyons that function as nurseries for nascent Gems. The Gems are created in the rock of these artificial canyons and leave their respective cocoons fully formed and ready to serve the needs of Homeworld. The process is destructive and intense, using up each new colonized planet's resources. The kindergartens leave planets ruined and barren, with Homeworld showing little regard for the life that already exists on their colonized planets. At this point, the Diamonds conquer another planet and start the process over.

Pink Diamond was not typically involved in Homeworld's colonial ambitions. Her role among the leaders of Homeworld reflected her personality. She was largely in charge of throwing parties and other celebrations, although that all changed when she begged her fellow Diamonds to allow her her own colony. They relented and assigned her to Earth, where she went about making new Gems in the traditional style. She set up kindergartens with the knowledge that they would use up the planet.

Pink Diamond's empathetic tendencies eventually overwhelm her when she takes a closer look at Earth. She realizes that the planet is teeming with living things and begins to question the idea of destroying the planet in service of her own people.

She takes a particular interest in the lives of human beings, and their ability to be whatever they please with no regards to the circumstances of their birth. Compared to the rigidity of Gem life, humanity's ability to follow their passions is downright blasphemous. Still, Pink sees the good in it and tries, unsuccessfully, to convince her fellow diamonds to call off the colony.

The Diamonds refuse, and urge Pink Diamond to carry out the job of using up and abandoning the planet, thereby destroying all of humanity and other life on Earth. The problem of destroying Earth weighs on Pink Diamond so heavily that she begins to think in ways that are entirely antithetical to Gems' rigid society and sense of duty. In short, this leader of the Gem home world finds her thoughts turning toward rebellion.

Pink Diamond decides to rebel against the Gem Homeworld in order to save life on Earth. While the story of how this happens is meted out slowly over the course of the series, it's relatively straightforward once it becomes clear.

Pink Diamond, knowing she's too much of a target to remain in her Diamond form and also be a rebel leader, fakes her own death with the help of her lieutenant Pearl, assuming the form of a rebellious gem named Rose Quartz after being "assassinated" on Earth. At the same time, Pearl begins to train as a knight, learning sword skills to fight the coming retaliation from Homeworld.

They found the Crystal Gems and declare themselves in open rebellion against Homeworld, at which point they began to enlist recruits among disenchanted gems who chafed against the strict nature of Gem society. The coming war between the ragtag band of guerrilla gems and the Homeworld empire will last thousands of years and end in a nearly unspeakable tragedy.

Blue Diamond invades Earth to take it back from the upstart rebel leader Rose Quartz, fully unaware that Rose is Pink Diamond. In one of the ensuing battles between Rose's band of Crystal Gems and Blue Diamond's shock troops, a fateful accident earns the Gems a new and valuable general.

Two of Blue Diamond's troops have been developing feelings for each other. However, they are forced to keep their attraction a secret, as fraternizing between different classes of Gems is considered vile by Gem society. Gems are able to merge with other members of their class to create more powerful "fusions." However, two different Gems merging is met with scorn and disgust.

While attempting to save her secret paramour from an attack by Pearl, a Ruby accidentally merges with a Sapphire creating the fusion known as Garnet. Combined, she has Sapphire's ability to see the future and Ruby's incredible fighting prowess. Still, rather than seeing this as a useful asset, Blue Diamond reacts with revulsion to their fusion. She orders that Ruby be "shattered" for fusing with a gem of higher status, in effect laying out a death sentence. Rather than submit to the sentence, Sapphire and Ruby join the rebellion on Earth, living in fusion as Garnet, and quickly become one of the Crystal Gems' most valuable fighters.

Very little is shown of the actual rebellion in the series. We see ruined landscapes and occasional flashbacks that let us know the war dragged on for eons. Many of the show's core characters are grappling with the effects of fighting a war that lasted for centuries. In one particularly revealing episode, Steven travels through the layers of Pearl's subconscious, uncovering more and more horrors that she'd suppressed so she could carry on once the war ended.

While the rebel Crystal Gems are almost comically outnumbered, Rose Quartz/Pink Diamond has the ability to heal injured Gems, and those who have joined her cause are cut down in battle only to be healed so that they can quickly return to fighting.

The rebels are armed by a blacksmith Gem named Bismuth, who is so filled hatred at the Homeworld Gems that she creates a weapon that would permanently destroy any Gem soldier. Rose Quartz reacts with horror at the idea of unleashing such a weapon, and is forced to put Bismuth in a permanent sense of stasis to keep her from using the weapon on their enemies.

Rose Quartz's decision to sideline her armorer is thrown into stark contrast by the machinations of the Homeworld Gems. The persistence of the Crystal Gems coupled with Rose's healing ability pushes the Homeworld leadership to unleash a truly horrific weapon on the Earth.

To end the war, Homeworld essentially nukes the planet. They opt to hit the Earth with a planet-wide blast from a weapon called the Corrupting Light. Any Gem on the Earth's surface caught in the blast would have their Gem, their very essence, permanently corrupted. While Gems have the ability to retreat within and regenerate in the event that they are grievously injured, the Light ensured that they could never recover. If the affected Gems attempted to regenerate, they would regain form as hideous and unintelligible monsters that are seemingly incapable of rational thought. The surviving Gems found themselves surrounded by their friends — who they had fought alongside for centuries — irreversibly morphed into terrifying beasts. 

The core members of the Crystal Gems are saved from the blast by Rose Quartz's defensive powers. She generates a massive shield around everyone in her vicinity, saving them from the effects of the Corrupting Light. After attempting to heal the corrupted Gems, only to have them regenerate as monsters, Rose Quartz makes the decision to quarantine her entire army. The Gems who were hit by the blast are held in an inter-dimensional graveyard until such a time as Rose can figure out how to heal them. Many thousands of the Crystal Gems' closest allies are held in this way for multiple millennia.

The war dies down after this blast, as the Homeworld Gems believe the Earth is now useless as a colony. Thinking that the rebellion had largely been quashed and their outpost to create Gems was ruined by the use of the Corrupting Light, they retreat to Homeworld and leave the Crystal Gems to pick up the pieces.

Not all gems being formed in Earth's "kindergarten" were ruined by the blast, as the Crystal Gems soon found out. They meet a runty Amethyst gem, who was protected from the Corrupting Light by a rock outcropping where she was being formed. She comes to join the Crystal Gems as they try to help Earth recover. While she is frequently viewed as an adult by Steven, the viewer's lens into the world of Gems throughout the show, she frequently struggles with the fact that she was not an original member of the rebel group and has no memories of the long war.

Amethyst comes across as the young adult of the Crystal Gems, frequently directionless but full of boundless energy for whatever catches her attention in a given week. She contrasts with the fastidious Pearl — Rose Quartz's most trusted aide — and the tactician Garnet, who plots out their battles with use of her psychic powers.

All together, the Gems move from a fighting band of guerrillas to an Earth-wide triage. They travel the planet capturing corrupted gems and "bubbling" them. The bubble prevents them from regenerating into aggressive monsters while Rose and her surviving comrades work out a way to heal them. They also ward off the occasional threat to Earth from passing Homeworld Gems and other cosmic monsters, protecting the planet that they defended for eons.

The problem of the corrupted Gems won't be solved until Steven ultimately finds a way to heal the divide between the Gems on Earth and the Diamonds of Homeworld in the show's closing episodes. The powers of all four of Homeworld's Diamonds are just enough to bring the corrupted soldiers back to life in their original forms. It takes the combined efforts of all four Diamonds to bring this about, and it occurs well after Rose Quartz is gone.

While the Gems continue to live on Earth, Rose's fascination with humans grows. She falls in love with a human, a rock musician who performs under the name Greg Universe. They decide to have a child and through a method that's never really explained, they create the show's titular character: a half-human, half-gem named Steven Universe. The creation process is the end of Rose Quartz, who subsumes herself into Steven's Gem. This gives the young Steven the powers of his mother, but none of her memories. Much of the series deals with Steven sussing out the history of his mother, who is also him. Other Gems still view him as his mother, and he has to teach them that he's someone entirely distinct while coming to grips with what his past self did.

The series as a whole starts well after Steven is born. The viewer and Steven learn the story of the Crystal Gems' rebellion at the same time. The full account of the war doesn't become clear until the final episodes of the show's five-season run.