A fanmade Alternate Universe of Steven Universe, where the positions of canon gems are swapped around, so the surviving Crystal Gems are Jasper, Lapis Lazuli, and Peridot, instead of Garnet, Amethyst, and Pearl. Jasper is usually depicted as the leader, Lapis Lazuli as the fun-loving one, and Peridot as the perfectionist. Sometimes Garnet is still a fusion and sometimes she's not, but she is usually The Brute of the Homeworld Gems. Amethyst is sometimes stuck in some gem device, but she's sometimes just living wild, like she was in canon before the Crystal Gems found her. Sugilite is the terrifyingly-unstable forced fusion of Garnet and Amethyst. Pearl is usually the low-ranking gem sent to check in on the Cluster.
Whether or not the swap extends to other gems is up to the interpreter. Sometimes Connie replaces Steven as the half-gem, but most of the time she doesn't. Sometimes Rose Quartz (called Pink Diamond in this case) is swapped with Yellow Diamond as the Crystal Gems' late, beloved leader and Steven's mother and the fearsome ruler of Homeworld, respectively. Sometimes Bismuth is included in the swaps, but this often isn't the case as the AU predates her introduction.
Has a fan episode, "The Smothering".
Tropes usually used in Momswap include:
- Antagonist Abilities: Inverted, as Peridot is normally portrayed as having her limb enhancers as a Crystal Gem, while Pearl doesn't get the assistive technology. Lapis also still has her powerful Making a Splash abilities.
- Arc Symbol: Stars and diamonds are still prominent symbols, but the characters who wear them have swapped.
- Depending on the Author: As with most fan verses, a lot does. The only real canon the AU has is that Jasper, Lapis, and Peridot are the ones raising Steven, rather than Garnet, Amethyst, and Pearl. Who they swap with isn't even consistent - usually it's Jasper/Garnet, Lapis/Amethyst, and Peridot/Pearl, but sometimes you can get Amethyst as the hulking Homeworld Gem or the limb-enhancer using technician, Peridot as the casual fun one, and Pearl as the one trapped in a mirror. There's also differing interpretations on who Steven is the son of. Some keep him Rose Quartz's son while others don't.
- Genki Girl: Lapis usually lacks most of her canon baggage and is thus portrayed as this, mirroring Amethyst.
- Irony: Rose Quartz being called Pink Diamond is even funnier when it's revealed that she is Pink Diamond.
- Mirror Universe: The fics swap the roles of the three originally introduced Crystal and Homeworld Gems, making it this.
- Unholy Matrimony: Ruby and Sapphire are usually portrayed as having this. They're still in love enough to Fuse as Garnet, but they're still as antagonistic as canon Jasper.