For 30 years, the jewelry designer David Yurman has used a simple twisted-metal cable motif as his signature. Instantly recognizable as a David Yurman design, the cable style has appeared in a multitude of jewelry and watch designs for men and women, from chunky sterling-silver men’s necklaces to delicate gold and diamond rings and bracelets. But his most striking cable designs are being unveiled now in celebration of the motif’s 30th anniversary. His internationally known jewelry brand has created a collectio…