Marilyn wears Ceil Chapman's floor-length off-white crepe gown with ruching at the hips and sleeves for photographer Philippe Halsman's photo session which garnered her first LIFE cover on April 7, 1952

Grace Kelly poses for LIFE magazine, photo by Philippe Halsman, 1954

Grace Kelly in duchesse satin gown by Edith Head, photo by Philippe Halsman for cover of Life magazine, Apr. 11, 1955

Close-up of Grace Kelly in aquamarine duchesse satin gown, designed by Edith Head, which she wore to accept her Oscar for best actress for "The Country Girl" in 1955, photo by Philippe Halsman.