They came, they saw, they bought. Our wrap-up of the best and the brightest jewels and news JCK Las Vegas 2012 had to offer.When we arrived at the Mandalay Bay Convention Center at the tail end of May for JCK Las Vegas and its sister events, LUXURY and Elite Enclave, we figured that year two at the show’s new digs would be smooth sailing. And we were right. The floor was crowded—the show has seen a 21 percent increase in attendance over the past two years—but in a good way. That made our annual effort to select JCK’s most note­worthy offerings not-so-smooth sailing. ­Tracking down the best diamond jewelry or the ­coolest men’s bridal bands was like searching for a gem-covered needle in a solid gold haystack: demanding—but in a good way.BEST DIAMOND JEWELRYPlevé Collection by Ron Rizzo for PluczenikGrouted diamond mosaic jewelry? It may sound strange, but that’s exactly