In the Spartan days of World War II, American women went without diamonds. Even after the armistice, ladies wore jewels only when going out on the town. But Harry Winston had a different vision. In 1946, he fashioned 219 diamonds (26.18 cts. t.w.) into this giant Maltese cross brooch. The next year, Carol Channing was singing “Diamonds Are a Girl’s Best Friend” on Broadway, and in Paris, Christian Dior debuted his New Look of ladylike, cinched-waist suits—all of which cried out for sparkly jewelry. “We were coming out of a dry spell,” says Joyce Jonas, president emeritus of the Ame