Steven Universe: The Gem War on Earth

What we know:

• Rose Quartz rebelled against the Gem Homeworld because she saw the beauty of it and didn't want the Homeworld to destroy it.
• Pearl chose to follow Rose into battle.
• Amethyst was recruited at the abandoned kindergarten, and some things about her, such as size, were not up to the standards of a usual amethyst.
• Rose, Garnet, Pearl, and Amethyst are the only surviving members of Rose’s army, to Jasper’s surprise.
• The remaining Gems (both Crystal and Homeworld) on Earth were corrupted and turned into monsters that Rose couldn’t heal.
• When the war was lost, the Homeworld left the cluster behind to destroy Earth millennia later. 
• Lapis Lazuli’s gem was cracked and stuck in a mirror.

Motivations:

I think that the war on Earth coincided with another event in Gem history, which would be the decision to use fusions solely as weapons. Why would an experiment on forced fusion be left to cook in the core of the Earth if fusion experiments weren’t another major Homeworld project?

This could shed some light on Garnet’s motivations. Peridot expresses discomfort with Garnet remaining fused outside of battle. In addition, when Garnet first deals with the Gem Shards, Ruby and Sapphire almost split, one of them wandering if it was their fault. I think that around the same time as Rose’s rebellion, Ruby and Sapphire chose to remain as Garnet as their default state. This brought Garnet under the scrutiny and persecution of the Homeworld Gems, which lead to her leaving to join Rose’s rebellion. Garnet is particularly hostile towards Homeworld Gems compared to the other Crystal Gems. Lapis is afraid of Garnet, although this could be because Garnet’s a full time fusion. The Centipeetle Gem is terrified of Garnet’s gauntlets, and Garnet is hostile to it in turn. I think that Centipeetle started as an anti-fusion Homeworld Gem.

If Jasper was on Earth during the Gem War, she fought because she opposed fusion. I think Jasper’s hatred of fusions is partially because fusion can make non-warrior Gems into warriors who might be able to defeat her. I’m not ready to say her motivations are pure loyalty, because “Jailbreak” shows that she is willing to act on her own agenda instead of Yellow Diamond’s. Why couldn’t they swing by the Cluster and check on it before heading back with Steven? Jasper made Steven's capture priority. In conclusion, Jasper fought for her beliefs about fusion and for the sake of fighting.

Lapis Lazuli was probably drawn to Earth because she is a hydro-kinetic gem, and Earth is mostly water. Before the war, there may have been attempts to put hydraulic energy to use for gem or weapon production. The potential failed project that I mentioned could be part of the reason that Lapis didn’t believe that Earth had potential. Regardless, Lapis didn’t want to stay on Earth, and the only way to go back to Homeworld would be to fight for the Homeworld. While Rose does operate on a morally gray scale, I don’t think that keeping Lapis imprisoned and injured in a mirror is something she’d allow. I don’t think this was done by any of the named characters. Lapis either was injured and captured by a Gem fighting for Rose then presented to Rose as a mirror, or Lapis was found injured by a Homeworld Gem and “recycled” as an object to spy on Rose with the false promise of rescuing Lapis later. The latter would explain why Lapis did at some point give information to the Crystal Gems, although the former would explain her hostility towards the Crystal Gems.

An Overcooked Amethyst:

The obvious side effect of Amethyst being overcooked is that she’s smaller than the standard quartz-type gem. Pearl calls her the one good thing that came from the Gem Kindergarten. I think that implies that Pearl (and probably Rose) felt that there was something “wrong” with the other quartzes made on Earth. Perhaps the Homeworld found a way to create quartz Gems that were naturally inclined to fight. Jasper is obsessed with strength and battle. Rose is motivated by her compassion, can create plant armies and heal, and is a skilled strategist making her a type of warrior-leader. Amethyst is light-hearted and goofy but plagued by a lot of self-consciousness that she tries to cover up with a laid back attitude. She’s also loyal but can chafe under too much authority, as shown in “Tiger Millionaire.” She's a capable fighter but can be reckless. These traits combined with her small size made her undesirable to the Homeworld Gems, and if they knew of her, she was probably abandoned.

Since she doesn’t know the role of quartz gems in society, she must have hatched much later than the other quartz gems, and that if any other gems hatched at the same time as her they were small kinds not meant for combat. Rose, as a fellow quartz, could have shared their ancestry but chose not to, probably because she either didn't want to keep the Homeworld hierarchy or was disgusted with the other quartz type gems made in the Gem Kindergarten.

Rose’s Army in the End:

Jasper is surprised that there are only three survivors of Rose’s army. The amount of hostile gems on a planet is valuable information that would have to be as accurate as possible, especially if they were sneaking noncombat gems on to check on the cluster. I say one or more because the Crystal Gems may not have known about Peridot if Steven hadn’t accidentally stuck his head out of the warp beam. The amount of enemies that could be faced would be passed on to Jasper, the warrior in charge of subduing the Crystal Gems. However, the small number surprises Jasper. This makes it seem like the Crystal Gems lost Gems between the first war and Steven's arrival.

My theory is that there were more who survived the Gem war at first, but they eventually became the corrupted monsters that Rose and the others fought to protect Earth from. Another possibility is that they could have artificially enlarged Rose’s army using Pearl’s battle holograms, but I find that one less likely. Surely the Homeworld Gems would be able to tell the difference. Also, I'm not sure if only her Pearl holograms were able to attack.