Ann Marie Dunn, co-owner of J.R. Dunn Jewelers in Lighthouse Point, Fla., says the best part of working with her husband, brother, son, and nephew is “the arguments we have.” How, exactly, can that be possible? “We decided a long time ago that whoever has the greatest passion about a subject wins the argument,” says the 70-year-old retailer, laughing. “Whoever quits first doesn’t have the passion, so we just keep going at it.” Clearly, an abiding passion for the fine jewelry business runs deep in the Dunn clan. Ann Marie and her husband, Jim Dunn, opened their first jewelry store in 1969—while both worked for IBM—out of a genuine love for jewelry and gems. Ann Marie’s brother, Robert Pelliccia, who was still a teenager when the couple first opened shop, has evolved into an award-winning jewelry designer under the couple’s shingle. In 1997, their son, Sean Dunn,