@tiny260 That’s a difficult question. The Doylist answer is obviously going to be “we made it work for the plot even if it’s difficult to make sense of”, but Doylism is rarely any fun, so my guess is very much like yours--sentience is a messy thing, and completely deleting the experiences that made the Gem a functional being would render that Gem nonfunctional. To completely erase their development WOULD require deleting basic functions, so the Rejuvenator has to leave bits and pieces; the process is so well-refined that it’s successful the vast majority of the time, but that’s more because other Gems are kept in line than because it’s an unbreakable lock. I’m sure it’s especially difficult with Gems as old as Pearl; she’s truly ancient, substantially older than human civilization, and that’s a lot of interconnected experiences to sift through.
From what I can tell, despite being the first, Amethyst was actually the most difficult of the three to restore! It was a much more gradual process than Garnet (whose single revelation was the core of her entire being) or Pearl (who really only required a little bit of a push once they figured out the actual trigger for her restoration). Steven figured out how to restore Amethyst right away, but it took an entire afternoon’s nudging to get her to a point where the secret handshake would push her over the edge. Amethyst didn’t come with a lot of the programming most Gems are born with, as evidenced by how she spent hours mirroring actions instead of conversing and asking questions. Restoring that functionality seemed to be important to restoring the rest of her.
