I finally found a picture of Jackie Bouvier’s debutante ball dress (worn in 1947)
It was an off -the-rack dress in tulle. Jackie wore this dress to a debutante ball she co-hosted with a fellow debutante Rose Grosvenor. Rose arrived in a Dior original but it was Jackie’s department-store ensemble that was dubbed “a designer’s dream.” Cholly Knickerbocker (pseudonym of Igor Cassini – yes the brother of Oleg) hailed Jacqueline “Queen Debutante of the Year (1947)”.
Of course only Jackie can strike such a pose and get away with it. The dress does set off her haircut and fit her well.