Perhaps not the first, but according to my professor of Fashion Photography, this was an early image that caused a minor kerfuffle because of its implied homoeroticism.
The image was by Bob Richardson, and was published in Harper’s Bazaar October 1965, p. 209. The caption read: “Daisy chains of diamonds, swaying in a net sweater that drapes in a cowl over the bodice of a white satin dress. Diamond flares, silver streaked, twinkling on a gauzy sweater atop a white dress. Both dresses by Mollie Parnis, in Staron Silk.”
"Giggling" by Bob Richardson, 1965
Chloe and Olivia: Lesbian Findings From History and The Arts 