New York painted in the colors of dawn. A taxi pulls up at 727 Fifth Avenue, dropping off a beautiful Audrey Hepburn who, as Holly Golightly, pauses to admire the window of Tiffany & Co., sipping coffee and eating a croissant. It is the unforgettable scene with which the movie Breakfast at Tiffany's (1961) begins. Unforgettable, just like the actress’s little black dress and spectacular necklace, embellished with a large yellow diamond, that forever sanctioned the link between fashion and jewelry. And that exact legendary diamond played the leading role at the “Yellow Is the New...