Marilyn Monroe may have sung that “diamonds are a girl’s best friend,” but one of her nicest—and most sentimental—pieces of jewelry was actually a simple string of Mikimoto pearls. Ballplayer Joe DiMaggio gave them to her during their 10-day Japanese honey­moon in 1954, which he would later describe as the happiest time of their marriage. And she wore the 16-inch strand of 44 akoya pearls, which fastened with Mikimoto’s signature gold clasp, often. Monroe even had them on, along with a black suit and long white gloves, at the Santa Monica, Calif., courthouse when she divorced the Yankee slugger on the grounds of mental cruelty only nine months later. “The necklace was one of the few pieces of ‘real’ ­jewelry that Marilyn Monroe owned,” says Meyer Hoffman, chief operating officer of Mikimoto America. Years later, the actress gave the necklace to her drama coach Paula