Mary-Kate and Ashley Olsen have certainly come a long way from their days on Full House, where the twins played one character, Michelle Tanner. But while the sisters began their careers with identical blonde hairstyles (and wardrobes), as they grew up, they developed their own individual styles--long and darker for Mary-Kate, and blond highlights for Ashley. But it was a long journey--full of a lot of experimentation with color and length. As we celebrate the Olsen twin's 31st birthday, here's a look back at their most memorable red carpet beauty moments.