They say third time’s the charm. And judging by the resounding success of JCK Las Vegas 2013 during year No. 3 at Mandalay Bay, they’d be right. Hailed by many exhibitors as the best show they’d had in years, this year’s JCK Las Vegas was a feel-good fest all around. It started May 28 with the opening of LUXURY and Elite Enclave, and carried on through June 3 at 4 p.m., when the lights at the Mandalay Bay Convention Center dimmed and people began to applaud and holler. In ­selecting our annual list of the best people, products, and promotions to be found in Vegas, the show’s palpable sense of ­optimism deserves top billing. But tiaras, tanzanite, and Adam Levine aren’t far behind. STONES OF THE SEASON Paraiba & Tanzanite Necklace in 18k gold with 191.41 cts. t.w. Brazilian Paraiba tourmaline and 7.87 cts. t.w. diamonds; $522,000; Lorenzo Jewels, Los An