He’s With the BandCraig Rottenberg, president of Long’s Jewelers, with five stores in Massachusetts, has a tried-and-true technique to help close more sales of platinum jewelry. It came in especially handy at Long’s annual Wedding Band Weekend event, held in late March at the 10,000-square-foot flagship in Burlington, Mass.Rottenberg calls his technique the drop test: He asks customers to extend their hands, with open palms, toward him; then he drops a gold and platinum band into each. People are surprised by the distinct difference in weight, as well as the negligible difference in price—less than $300 per ounce at press time (one guess which metal is costlier).“Sometimes the first thought of customers, particularly men, is that they don’t need to put a lot of money into a band,” explains Rottenberg. “But the price difference is not as big as it used to be, so it’s a s