Couture (Geneva) A few years ago, museum-goers were tantalized with a once-in-a lifetime exhibit on diamonds. Now, the American Museum of Natural History, New York, has turned its attention to the pearl, producing one of the most comprehensive displays on this gem from the sea. The exhibit, which opened October 13, examines the natural history of pearls, weaving science, art, literature, history and jewelry together. Highlights include: Black and white pearls from marine Pinctada oysters from Japan and Polynesia; freshwater pearls from mussels found in the United States and China; luminous pink conch pearls from the Caribbean Queen Conch, a collection of unusual pearls from the orange Horse Conch and the Giant Clam; and, little known fossil pearls and 70 million-year-old ammonite shells, both of which have retained their original iridescent nacre. One section features jewelry and decorative objects including both old and new designs. Among the few modern pieces included in the exhibit is a brooch designed by Ellagem, New York. The exhibit runs until April 12, 2002 and will then travel to Chicago's Field Museum, where it will be on view from June zs, 2002 through January 5, 2003.