The Gems of Steven Universe: Homeworld, the Diamonds, Fusion and How a Gem Is Made

Steven Universe premiered on Cartoon Network on November 4, 2013, created by Rebecca Sugar, the first woman to create a series for the network on her own, and its aliens were unlike any on children's television. The Gems are gemstones that are alive: each one's body is a hologram of hard light projected from the stone, which sits somewhere on the body as its only vital part, and each is defined by what kind of stone it is, a Pearl made to serve, a Ruby made to fight, a Sapphire made to see the future, a Jasper made to conquer. They come from Homeworld, a planet of towers and spires ruled by the Diamonds, and they have colonised the galaxy by making more of themselves in the crusts of other worlds. Three of them, Garnet, Amethyst and Pearl, live in a temple on the beach of a small American town, Beach City, raising a half-human boy named Steven, whose mother, Rose Quartz, gave up her physical form to bear him.

The series ran for five seasons to January 2019, then a feature film in September 2019 and an epilogue series, Steven Universe Future, that ended in March 2020, and it built, across that run, a complete alien society with a caste system, a theology, a war and a reconciliation. Its Gems are the field guide's only species whose biology is mineral, and the only one whose central question is whether a being made for one purpose can choose another.

Gem society is a hierarchy of stones. At the top are the Diamonds, enormous, radiant and near-omnipotent, each ruling a court of Gems in her colour; below them the noble Gems, Sapphires and Aquamarines; below those the soldiers, Quartzes and Rubies; and at the bottom the Pearls, made as servants and ornaments, and the Peridots, technicians. A Gem's place is set by her stone and her cut, and the society's crime is to be off-colour, defective or fused with a stone of another kind. Homeworld expands by colonisation, and colonisation means the Kindergarten: injectors drilled into a planet's crust that seed it with Gems, who draw life from the rock as they grow, so that a colonised world is hollowed and dead by the time its Gems are finished. Earth was Pink Diamond's colony, and the Kindergartens in its canyons were where the show's Amethyst emerged.

The Crystal Gems were the rebellion against that. Rose Quartz, the show's founding legend, raised an army of Gems who loved the Earth against the Diamonds, fought a war five and a half thousand years ago that ended when the Diamonds unleashed a weapon that corrupted every Gem left on the planet into a monster, and the survivors, Garnet, Amethyst, Pearl and Rose, spent the millennia since as its guardians. The 2018 episode "A Single Pale Rose" revealed the twist the series had been built toward: Rose Quartz was Pink Diamond, the colony's owner, who had rebelled against her own empire in disguise.

Fusion is the Gems' most important biology and the show's most important idea. Two or more Gems who dance in sync can merge into a single larger being with a combined form, a new name and a new personality, and the series treats the act as everything from a battle tactic to a marriage: Garnet, the Crystal Gems' leader, is a permanent fusion of a Ruby and a Sapphire who chose each other on Earth and never separated, and the 2018 wedding of the two, in a Cartoon Network series aimed at children, was the episode the show is most cited for. Fusion between Gems of different types is Homeworld's deepest taboo, and the rebellion's deepest principle; Steven, half human, can fuse with his friend Connie into Stevonnie, which nobody on Homeworld had thought possible.

The Gems' bodies are the other half of the idea. A Gem chooses her form, can change it, and reforms after damage with a new one, so that identity in the series is something projected rather than given; Amethyst, who came out of the ground small and wrong by Homeworld's standard, is the show's argument that the standard is the defect. Sugar built the series, she has said, out of her own experience, and its Gems are a species designed to ask what a person is when the body is optional.

Life made of mineral is an old question with a short scientific answer. Silicon sits below carbon on the periodic table and forms similar bonds, and the idea that life elsewhere might be silicon-based has been in science fiction since the 1890s and in Star Trek since the Horta of 1967, a rock creature that turned out to be a mother; the case against is that silicon's compounds are far less flexible than carbon's and that its oxide is sand rather than a gas that a body could breathe out, which is why astrobiologists searching for life look for carbon first. The do aliens exist article covers the search. The Gems, being light projected from a stone, sidestep the chemistry entirely, which is the show's privilege.

The crystal is the lore's object too. The channelling literature of the 1980s and 1990s gave the Pleiadians crystal technology and crystal cities, crystal skulls were sold as alien artefacts, and the beings of the new-age contact books tend to arrive in ships of light with messages about vibration; the Gems' Homeworld, with its spires and its hard-light bodies, is that imagery organised into an empire and then criticised. The Kindergarten, a colonisation that kills the planet, is the same crime as the Reapers' harvest in Mass Effect, told from the side of the colonists who refused; and Steven, a child of two species who is more than either, is the hybrid the abduction lore fears, drawn as the hero. The Kryptonians are the other family of superhuman aliens whose home world's rigidity destroyed it.