Mirror Diamond

Mirror Diamond is a version of Diamond seen inside a mirror during "Alpha Diamond". She appears to tell Diamond about how she turning into someone else entirely amuses her.

Appearence
Mirror Diamond looks exactly like Diamond in her season 1 clothing, though reversed since she's in a mirror when she's seen.

Personality
Unlike Diamond, Mirror Diamond has the job of making her other one to feel bad after turning into an Alpha Girl. Outside of that, not much of her personality is known but it can be said it's the opposite of Diamond's.

Diamond Dreizler (Other self)
Diamond is the only one who Mirror Diamond interacts with. While not much is shown in their conversation, Mirror Diamond likes to mess with her other self.