[@Saarebas] [@Raijinslayer]
[s] That's basically my theory, except that it's not exclusive to gems of Rose's rebellion, but to gems of either side that have become this twisted/confused/hopeless/etc. Gems don't even need to have been part of the war to become corrupt; it can happen to any gem if in the right circumstances, though the ones Steven and co. encounter are from the war since they're on Earth and whatnot. I like to think of corrupted gems as sort of parallels to witches in Madoka Magica, but ye.[/s]