JCK studied directional designs for 2013—on the red carpet, on the catwalks, and in new jewelry collections—to draw up a list of 10 trends that retailers need to knowTrend forecasting can be a tricky business. Still, those with a knack for seeing the future a few months or years ahead are sought after for their ability to steer businesses onto profitable merchandising paths.At the risk of tooting our own horn, you’re in luck. JCK has a proven track record in supplying spot-on jewelry market intelligence, so we polished up our crystal ball to once again divine the must-know jewelry and fashion trends that will guide style decisions in the year to come:Green MachineUnless you’ve been in hibernation, you’ve heard the big news: Emerald is the color of the year, replacing last year’s citrusy Tangerine Tango, according to New York City–based color institute Pantone. For shoppers