This gown has a interesting history. It was first designed by famed costume designer Adrian for the film Marie Antoinette.
Several years later, Ava Gardner was photographed by Man Ray while wearing the gown. One of those photos was used in the film in order to create the miniature of Ava that is seen in the film. Ava seems to have liked the photograph, and appparently had a painting based off of the photo commissioned by artist Antonio Diaz.
The third time the gown was used was in the famous fight scene in Scaramouche.
The gown is now in the collection of Mary Strauss. To learn more about where the gown is on display, go here. To learn more about the photographs of Man Ray and Ava Gardner, go here. To see the listing for the painting in the Ava Gardner estate, go here.