Board Thread:General Discussion/@comment-25365147-20150410015711

In "Story for Steven", the Crystal Gems look noticably younger. But in "So Many Birthdays", the photo of them has them looking the same way they do now, and in "On the Run", Amethyst's hole was the same size as her adult form.

We know Steven's physical age changes based on how he feels. I think the same thing applies to all Gems, though they control it consciously. Before Steven, things looked pretty peaceful, and they had Rose with them, so they might've taken younger forms. They also behave differently to each other, again suggesting "mental age". The responsibility of taking care of Steven probably encouraged them to take older forms.

It's also possible that their default form can change drastically with each regeneration, again reflecting mental state. The first time we only saw an outfit change with Pearl, but when Garnet came back together, she was a slightly different color, more of a purple tint than red, better reflecting her fusion nature. I think being split apart made her better appreciate being together, so her new appearance better reflected both of them. And Peridot always has bags under her eyes, and she's the only Gem who looks like that. She seems to be very focused on her work, and easily stressed out, so her appearance reflects that. Maybe if her attitude changes, so will her appearance if she regenerates. 