It took more than a pair of colored contacts to transform Kristen Stewart's "Twilight" character, Bella Swan, into the vampire Bella Cullen.

As the 22-year-old actress explains in a special feature clip from the DVD/Blu-ray edition of the final "Twilight" installment, she had to ditch the quirks that came naturally to her in order to portray an assured, super-strong and speedy vamp.

"I've yet to play somebody who was a huge departure for me. I mean, to be completely still and controlled, and to know that your mind works faster," Stewart said of the character transition. "Being a clumsy person, it's not the easiest thing to do. The way I usually learn my lines is I learn the idea, which is why I stutter a lot in 'Twilight.'"

"The Twilight Saga: Breaking Dawn - Part 2" will be released on Blu-ray, DVD, digital download and video on demand March 2.