With the ubiquity of mobile phones—and their inevitable distractions—­jewelers may be tempted to remove them from the sales floor altogether. But savvy retailers and designers know smartphones can work to their advantage when text messages, email, and picture-sharing are used to spark sales. Whether or not your store has a dedicated e-commerce website, real-time communication with existing customers on mobile devices can bring in business that otherwise would not exist.At Christensen & Rafferty in San Mateo, Calif., contacting clients on their mobile phones is commonplace. “Connecti