10 buys to make at JCK Las Vegas this year1. THE COLORS: Blue & GreenSpring was all about flirty, carefree pastels, but come fall, ­jewelry takes a darker turn toward a bolder and richer palette. The two standout shades of the season? Here’s a hint: ­Remember Angelina Jolie’s long-sleeved green Atelier Versace dress at ­January’s Golden Globe Awards, a perfect complement to her 27 ct. emerald Robert Procop ring? No serious student of the red carpet needs to be reminded of the recent ubiquity of green, and the ­color’s reign shows no signs of abating. Blue, meanwhile, was a runway favorite among style setters such as Diane von Furstenberg, whose head-to-toe royal blue ensembles were an editorial favorite. To satisfy fans of both shades, think wide and deep in terms of gems: sapphire, sodalite, and dyed pearls for azure hues; tsavorite, tourmaline, and malachite for ­clove