Since fusion is such an important part of the plot of Steven Universe, I think it’s about time we all got on the same page about it.

Let’s talk history here

Prior to 5750 years ago, gems only fused with other gems of the same type. This practice was a sanctioned technique that allowed weaker foot soldiers like rubies to increase their own strength in combat

Jasper: Fusion is just a cheap tactic to make weak gems stronger

When Ruby and Sapphire fused for the first time in The Answer, they caused a major problem for homeworld

Homeworld has a very strict hierarchy where rank is defined by a gem’s type. Diamonds are queens by virtue of being Diamonds, Sapphires are nobles because they are Sapphires, and Pearls are slaves due to the fact that they are Pearls.

When two gems of different types fuse, they become a third type of gem. This action completely breaks the caste system, making it possible for low-class gems to fuse into higher classes, which is why homeworld made it a taboo punishable by death. It also tells us something else important: There are no fusion-only gems. That is to say that there are Garnets and Opals out there that aren’t a fusion of two or more gems. They’re just a single gem with a single stone.

We know this because mixed-gem fusion would not be taboo if homeworld could simply say, for example, “Opals only exist as fusions of Pearls and Amethysts, so they should have the same rank as a Pearl”. The fact that it’s against the law means that gems like Opals and Garnets are already somewhere on the social pyramid, and that means they must already exist in a society where mixed-gem fusion isn’t a thing. But this isn’t the only reason we know this.

In Cheeseburger Backpack we see at leas three separate gem statues with four arms. All of these were in the Lunar Sea spire, a gem oasis that we learned was built by homeworld in It Could Have Been Great. Since homworld hates mixed-gem fusions, they probably wouldn’t make sculptures of them. In other words, these could be sculptures of gems like Opals who normally have four arms. The existence of non-fusions with extra parts shouldn’t be all that shocking since we’ve seen plenty of gems with missing features, such as Sapphire’s single eye

Due to the events of The Answer, Homeworld seems to have refined its policy on fusion in order to prevent political upheaval. First and foremost, it seems fusion was no longer strictly taboo, since both Peridot and Jasper were easily convinced to try it, but it’s still pretty clear that Homeworld still only allows fusion for combat

Peridot: She’s not even fighting! She’s, you know, she’s just, y-you know like the… *pounds fists together* you know!



And second, fusions are no longer considered to be real gems.

Peridot: No, really, Pearl is a pearl, Garnet is a fusion, I don’t even know what he’s supposed to be! *points at Steven* Steven: Hey! Peridot: You’re the only Crystal Gem, that’s actually a Gem!

This effectively solves the gem-mixing problem for homeworld, and even sanctions its use in certain situations where it would be beneficial to homeworld to do so.