The Earth was Pink Diamond's colony. Everything was going smoothly at first. Kindergartens were incubating their first soldiers. Big, warm pieces of Quartz, like this mountain over here, were being created from its rich minerals with great success. Then — bam! One of Pink Diamond's very own Quartz soldiers started a rebellion and took it too far.
|—Eyeball, in "Back to the Moon"|
Earth, also known as "Crystal System Colony Planet Earth", is an abandoned Gem colony planet and the primary location of Steven Universe. Earth contains many native species, with the dominant, sentient species being humans. This Earth exists in an alternate universe, and while it is apparently similar, there are many differences.
Over 5,750 years ago, Homeworld Gems decided to have their next colony on Earth. Under the leadership of Pink Diamond, and supervision of Blue Diamond, Gems traveled to Earth in Era 1 Colony Ships. There, they began to build a variety of structures such as spires, arenas, temples, and other buildings which would serve the purpose of benefiting Gem life while on the Earth colony. Homeworld Gems also created Warp Pads, which would allow Gems to travel from place to place on Earth quickly, and even travel off-planet to other Gem colonies and the Gem Homeworld itself. A base was constructed on the Earth's moon, which was used by the Diamonds and other Gem elites to monitor the Earth's colonization progress.
The primary purpose of establishing a Gem colony on Earth, however, was for Homeworld Gems to use the planet's rich and unique organic minerals to manufacture new Gems. The first Kindergarten on Earth, better known as the Prime Kindergarten, was established to serve the purpose of creating new Gems. With great success, the Prime Kindergarten efficiently popped out Gems, many of them being of the Quartz variety. Pink Diamond also used the Earth's materials to create a whole new class of Quartz Gems: Rose Quartzes.
One of Pink Diamond's Rose Quartzes took note of how the Prime Kindergarten was damaging the Earth, since incubating Gems sucked the life force out of the ground around it, which would ultimately cause the planet to be uninhabitable for organic life. Believing it was unfair to the life already present on Earth, Rose Quartz rebelled against the Homeworld Gems, forming the Crystal Gems (a rebel group who agreed with Rose Quartz's beliefs). The Crystal Gems fought a 1,000-year long war against the Homeworld Gems, in an event titled the Rebellion, and won, successfully driving Homeworld Gems off of the Earth.
During the Rebellion, Homeworld Gems remained mostly dominant and were thus able to continue creating Gem structures, such as the Pyramid Temple. However, halfway through the war, Homeworld Gems struggled to keep up with Rose Quartz's army, since Rose Quartz could heal her wounded allies. They created the Beta Kindergarten to quickly generate more soldiers on the ground, which made the Beta Kindergarten a rushed job, and many of the Gems manufactured there came out defective.
At some point, Homeworld Gems no longer saw Earth as a viable colony, due to the powerful Crystal Gems defending the planet. Instead, they decided to use the planet for a different purpose, unbeknownst to the Crystal Gems. As punishment for the Rebellion, Homeworld Gems collected the shattered remains of fallen Crystal Gems, with the goal of fusing all of the Gem Shards in a power weapon. To understand how to fuse Gem Shards together, Homeworld Gems created some prototypes for the Cluster and stored them in the Prime Kindergarten Control Room. Once testing was complete, Homeworld Gems moved on to fuse millions of Gem Shards together, which would take thousands of years to take on its physical form. At the Beta Kindergarten, Homeworld Gems inserted the Cluster deep into the Earth's mantle. The goal was for the Cluster to take on its physical form, which would completely destroy the planet inside-out.
As previously stated, the Crystal Gems ultimately warded Homeworld Gems off of the planet, with only 5% of the colony completed (according to Peridot). If the colony was finished, many more structures would have been built, including 89 Kindergartens, 67 spires, and several Galaxy Warp stations. Also, the Earth was to be hollowed out down to the core, with large sections of the crust removed to make the most of its resources. However, due to the Rebellion, this plan was abandoned and replaced with the plans to create the Cluster.
Maps of the globe seen in the show consistently depict significant geographical differences from real-life Earth:
- The Floridian Peninsula of North America is a series of small islands cut off from the mainland. Otherwise, the physical outline of North America on maps has not changed as drastically as some of the other continents.
- The entire Central American area is fragmented in a large group of islands.
- The eastern side of South America — loosely corresponding to Brazil — is noticeably larger than in real life, jutting out east into the South Atlantic.
- West Africa is now covered by the ocean. In fact, the new west coast of this alternate Africa seems to match up with the shape of the larger east coast of South America — just as in real life, the coasts of Africa and South America visibly seem to match up, because they were pushed apart by moving tectonic plates. It is possible that the mid-Atlantic fault line that separated South America from Africa is further east in the Steven Universe Earth due to differing geologic activity.
- A large island and two smaller islands can be seen off the South Atlantic coast of eastern South America, forming an island chain between it and Africa (ending around where Nigeria would be).
- Iceland does not exist.
- Greenland is slightly further east than in real life, making the Baffin Bay larger.
- Russia is missing a huge chunk of land area in the middle of Siberia — the size of Europe. Conspicuously, it is shaped like a neat circle, and a Gem facility is in the very center of it according to the map in the moon base.
- This Gem facility is at the same place as the Tunguska event (a presumptive meteor air burst in 1908).
- The Indian Subcontinent has been almost bisected horizontally by the ocean, in effect making the southern half a separate island (separated from the mainland only by a long but narrow inlet).
- Similar to India, Australia has been bisected vertically by the ocean, splitting it into two separate islands. The coastlines of the eastern island are what they are like in real life (except for the new western coast), but the ocean has flooded much of the western island.
- The ocean has flooded much of southern China's coast.
- The Balearic Islands look remarkably different, and they are located near the northern coast of Africa, instead of the southern coast of Spain.
- The Great Lakes seem to be more interconnected.
- Japan's islands seem fused together, with the northernmost (Hokkaido) forming a land bridge to mainland Asia through Sakhalin, but it is not clear if they are intentional or just due to the outlines of land masses appearing blurry on a large world map in this animation style.
- The Philippines appear to be much further west, almost touching Borneo.
- The coastline of Eastern Asia has drastically changed.
- The Polynesian islands are in much different positions. Indonesia and Malaysia are slightly closer together, and there are multiple new islands.
- As seen from the Moon, the shadow and light from the sun on Earth meets at the equator, which may imply the planet has an entirely different rotation and axis than real life. In other episodes, the shadows are normal, and this could be animation errors.
Homeworld Gems appear to have divided up the Earth into different sections, labeling them as 'Facets'. Each Facet name is followed up with a number which differentiates the several Facets. One of the Colony Plans was to have a Galaxy Warp in each Facet.
- Facet 5 – The Prime Kindergarten is located in Facet 5.
- Facet 6 – Eyeball states that she was in Facet 6 halfway through the Rebellion when Jasper formed.
- Facet 9 – The Beta Kindergarten is located in Facet 9.
There are several historical differences between Earth in the show and Earth in real life.
- Delmarva is a state, in which Beach City is located. In real life, this is just a term for the large peninsula on the east side of Chesapeake Bay, because it is shared by the states of Delaware, Maryland, and Virginia.
- In real life, the U.S. state of Pennsylvania is nicknamed "the Keystone State". In the Steven Universe world, it is officially named "Keystone" (though otherwise, it has the same borders as real-life Pennsylvania).
- Kansas is a major hub of the movie industry, with Kansas being SU's analog for Hollywood.It could also be that, because state names in the U.S. are different, Kansas may be the name of California and vice versa.
- The real-life state of "New Jersey" is named simply "Jersey".
- The real-life state of "New York" is named "Empire State" (as seen on official road signs). As with Pennsylvania/Keystone, "the Empire State" is the official nickname of New York state in real life.
- Major American cities include Charm City, Wilmingmore and Empire City.
- Charm City is a real-life nickname for Baltimore, Maryland.
- Wilmingmore is a portmanteau of the names of Wilmington, Delaware and Baltimore, Maryland.
- Empire City is their direct geographical analog of New York City. "Mr. Greg" confirmed that it contains locations like Brooklyn and Bowery, areas in real-life New York City. Culturally/historically, however, "Empire City" is sort of "a fusion of New York City, Paris, and Las Vegas".
- Currency appears different in this timeline: some coins have Gadsden-like snake symbols or pictures of a woman resembling Pearl. $1 bills have images of an upward-pointing diamond on the left and a Gadsden-like snake symbol on the right. $3 bills also exist in this world.
- Instead of the FBI, there is the Department of Justice: Federal Bureau. Their symbol has 12 stars instead of 13, and instead of a shield surrounded by laurels, there is a snake resembling the one from the Gadsden flag, accompanied by a waning crescent moon symbol.
- The Canadian flag is green and white, instead of being red and white.
- Well-known holidays such as Christmas or Halloween do not exist as such in this world (though there are some generically similar holiday periods).
- Judaism still exists in this world.
- Korea exists and shares the same flag as South Korea, though it is unknown if it is split into North and South governments like in real life.
- World War II has not happened.
- Italy exists but is instead called Italia.
- Aqua Mexico exists (according to Steven in "So Many Birthdays") and is likely a replacement for Mexico.
Environmental influences either caused by the Gems or by geological differences.
- Pears are not very appreciated and are also very uncommon, growing only on the coasts of Eastern Europe and North Africa.
- The mass production of durian juice would imply that the durian is much more common.