Beautiful fabric and expert tailoring make even a simple gown supremely luxurious. White silk faille Watteau-back knee-length cocktail dress with ostrich feather petticoat, $3,750 by Oscar de la Renta. Ivory felt pearl beaded headpiece (by special order), price upon request, Temperley London. White and gold South Sea pearl necklace with rubies, emeralds and diamonds, $64,800 by TARA. Long-strand white cultured pearl necklace with gold, platinum, ruby and diamond clasp, $47,000 by Oscar Heyman, 800-642-1912.