You’d never know by looking at Jean Vanderbilt (née Harvey) that she comes from a family of meat packers and hamburger hawkers. You also wouldn’t guess that her two glittering Van Cleef & Arpels pearl, diamond, and yellow gold bracelets could become a necklace by joining their decorative clasps. That’s not all: The pearl strands, laid flat in this photo, also could be twisted to make the final piece longer or shorter.“Transformation was a signature of Van Cleef & Arpels,” says Nicolas Luchsinger, the jeweler’s retail director. “Pieces transformed from bracelets to neckla