Precision gem cutting is essential to bringing out the beauty of a faceted pearl. The loose white and pink Chinese freshwaters, one golden South Sea, and three black Tahitian faceted cultured pearls are all fine examples, courtesy of Pala International, Fallbrook, Calif. The well-matched, graduated strand of Tahitian black faceted cultured pearls is courtesy of JOEB Enterprises, Solana Beach, Calif. Pearls have been coveted for thousands of years. They've been used whole, drilled, and cut in half, and they've even been ground up and eaten. And since 1998, they've been faceted. Faceting a pearl can bring out the best in a somewhat blemished but otherwise nice-quality pearl, even though in most cases the blemish will still be visible. The finest-quality faceted cultured pearls, however, start with top-quality pearls that combine virtues of color, luster, and nacre thickness. But faceti