At the helm of JCKMarketplace.com, the new online sourcing tool that allows you to shop for inventory like you’re walking the aisles of a trade show, is ­marketplace manager Brittany Siminitz. From her base in Washington, D.C., Siminitz, a former retailer—she spent nearly four years at Joint Venture Jewelry in Cary, N.C.—talks about her first major sale, her favorite trend, and how being compared to a piece of candy is actually a compliment.How long have you been in jewelry?I got into jewelry right out of college, four years ago, with my first job at a retail store, working with marketing and social media. I’d always wanted to be in fashion and never thought I’d get into jewelry, but I grew to love it so much.What was your first major sale as a retailer?I was working with an older woman, probably in her late 70s. She went through the entire store for what felt like hours. I wa