Kristen Stewart is pretty, that's for sure.

But her makeup artist, Robin Mathews, says The Runaways star, 19, is more than just a pretty face.

"She's the most chameleon-like actress that I’ve ever witnessed," Mathews tells Nylon magazine. "She can play a beauty or a wreck at the same time if she wants to... She just has a bone structure that allows her to be morphed into other things easily."
Still, that didn't mean it was easy for Stewart to turn into Joan Jett -- and for Dakota Fanning to become Cherie Currie -- for the recently released biopic.

"For The Runaways, we had binders in the makeup trailer with about 5,000 photos total, and then I lined the entire trailer with tons of photos of Cherie Currie and Joan Jett," Mathews says. "It was really important to get them to look as close to the real characters as possible, which meant doing a lot of chiseling."
Mathews -- who has also worked on the second and third installments of the Twilight movie franchise --even admits that she used "some prosthetic appliances" to complete Stewart's transformation.

The makeup pro also admitted that Kristen's turn as Bella in Twilight and New Moon was "tricky" because she "had to be a naturally pretty girl" surrounded by mythical vampires.
"She needs to be plain but beautiful at the same time," she says. "It’s all about the flawless skin and a naturally pretty cheek color."

Which was harder -- Joan Jett or Bella Swan?

The Runaways, she says, adding that it's difficult "recreating real people, icons."