I read this book in the mid 90s that was about two girls, one a good girl with perfect grades, the other a troublemaker who is sort of Goth. The good girl has to be a "therapist" of sorts at school to the other, and they slowly end up friends. The bad girl turns out to be a rich kid who is a great pianist, while the good girl has a bad homelife with a mother who doesn't work and a kid sister no one takes care of. Does anyone know the name of this book? I remember the title having something to do with colors but nothing else.