The third generation’s the charm at 92-year-old Levy’s Fine Jewelry in BirminghamThere’s a point in every long-standing family business where its very existence looks shaky. For Charles Denaburg and his sister, Rhoda Denaburg Link, co-owners of Levy’s Fine Jewelry in Birmingham, Ala., it was after the 1972 death of their father, Joe Denaburg, who founded Levy’s in 1922. Charles, a lawyer moonlighting as a jeweler, kept things going. Ten years later, Rhoda, who’d been living (and running a jewelry business) in Chicago, returned and teamed with her brother for a complete store overhaul, transforming Levy’s into a destination for bridal and estate jewelry.Today, their kids, Jared Nadler ­(Rhoda’s son) and Todd Denaburg (Charles’ son) do the heavy lifting at Levy’s—and business is booming. Still, Charles spends his lunch breaks and evenings at the store. Rhoda—whom J