[@Peridot] [@Akayaofthemoon] I'm a little late to the party on this, but I wanted to say something about Carmen's history and being called a gem by other kids;

In Steven Universe, Beach City is a small town. These people have grown up with some big, imposing statue standing over their homes and businesses. Occasionally, rather colorful (and I mean that literally and figuratively) have come out of it to take care of some creature that's terrorizing the town. Amethyst took things a step further and befriended at least one person in town that we know of (Vidalia). Its a small town, and These people know enough about the gems to just accept them as a part of life. They've always been there and they've (mostly) not done any harm to people or property.

In empire city, the only people they interact with are the hotel staff, and the entire musical number once they get there definitely points out that the staff don't give the slightest shit about whoever comes in, so long as the individual can pay up. It's by no means a good gauge of what outsiders think about gems.

Now, we have Crystalisis. Completely new turf, with a scenario never mentioned in the show. People have been born and raised in a city that was built on top of a gem production facility. Their structures and tools have got to be all over the place, the scars of battle from the rebellion war catalogued and recorded in history books. Stories of grotesque creatures that spawned after it have to be lurking around everywhere, too. Of course the people of crystalisis know about the gems. They've lived atop what they left behind all their lives, heard about gem mutants, learned about the war in history books. Kids are mean. We know this. It's not hard to imagine a group of them learning more about gems, and picking on the odd kid out because he has a different appearance.