Iman is nothing if not polite, as evidenced by her first sitting for Richard Avedon more than 20 years ago. “Seeing as I just came from Africa, I didn’t want to be presumptuous that I was a friend. When I got on the set, I said, ‘Should I smile or not Mr. Dick?’” the supermodel recalled during a dinner at Christie’s on Thursday night, co-hosted by Iman, Allison Sarofim and Lanvin and celebrating the house’s auction of Avedon’s work. “He said, ‘Ok, stop everything. I know you just came from Africa. You can call me Dick or Mr. Avedon—but never Mr. Dick.” The collection of 65 photos will be on view at Christie’s New York from October 1 through 6. They will be sold at Christie’s Paris on November 20.