*WARNING MAJOR SPOILERS*
You should watch Steven Universe before reading this. Or don’t. I don’t care what you do.
Today, we’ll be exploring The Great Diamond Authority Theory from Steven Universe. This theory pretty much states that Ronaldo Fryman’s theory was correct at the end of episode 31, “Keep Beach City Weird”, and he began to discover how The Gem Homeworld works.
After learning that Steven and the Gems were the center of everything weird going on in the city, Ronaldo formed a new theory, that he called, The Great Diamond Authority.
Once the epiphany of polymorphic sentient rocks (pretty much what gems are) he thought that maybe these rocks are trying to “hollow out the earth”, which we later learn is what Homeworld was trying to do, in order to create more gems, thousands of years ago, until Rose Quartz and the rebellion stopped them.
The theory goes along with the Multiple Gems Theory, and the Gem Caste System Theory. These theories state that there are more than one of each gem, and that each type of gem are placed into some kind of class on Homeworld. For example, Pearls are servants, Peridots are technicians, Quartz are warriors, etc. These theories were confirmed in the episodes “Back to the Barn”, and “Too Far”.
Going by the Diamond Authority Theory, that means that Diamonds are the rulers of Homeworld. The theory states that there are four diamonds, Yellow, Blue, White, and Pink. We don’t know much about the first three, but according to the theory, Pink Diamond was Rose.
Each Gem holds allegiance to one of the four diamonds. For example, Peridot and Jasper follow Yellow Diamond, shown by the yellow diamond symbol on their uniforms,
and The Crystal Gems follow Pink Diamond shown by the star symbol they wear. But, they also might’ve used to wear a pink diamond on their uniforms as shown by Pearl’s Space Suit, and Holo Pearl's uniform.
This theory is greatly hinted at and supported by the show in many episodes. Like, in one of the earlier episodes, “Serious Steven”, a mural is shown that depicts Rose Quartz fighting three gems that look like yellow diamond, white diamond, and blue diamond.
Or in “The Return”, when Jasper directly mentions Yellow Diamond. And, the numerous times that we see the Diamond Authority symbol throughout the show