The Story Behind Keira Knightley's Emerald Green Slip Dress From 'Atonement' British Vogue Keira Knightleys emerald green dress in Atonement (2007) has become one of the most iconic costumes in film history. Designed by Jacqueline Durran, the silk gown perfectly captured 1930s elegance She walked into the room, and time held its breath. Keira Knightley's emerald silk in Atonement (2007) wasn't just a costumeit was cinematic seduction. Named the best movie dress of all Keira Knightley Source on Instagram: I've always found these dresses quite similar, but the green dress from 'Atonement' will forever be my favorite. Which one do you