Honestly Rose being Pink Diamond makes the most sense to me. Tbh I don't know why everyone calls it Pink Diamond though, it's not like anyone on the show has said it. I know the symbol refers to the Diamond Authority but I still don't think that was her name. She's a Quartz, not a diamond, but she is clearly powerful as she had both a sword and a shield and she also was able to lead an entire rebellion and win a war. I also believe Rose is the one who ordered for the Kindergartens to be built on the planet and when she saw what it was doing to the planet she rebelled against it.

Actually, if that's the case then Rose and Peridot are very similar actually. I'm sure Rose didn't just full out try to start a fight but instead tried to talk to Blue Diamond (the one in charge of the colonization of Earth) and tried to cease the colonization, but when Blue Diamond refused she rebelled, very similar to what Peridot did to Yellow Diamond.