Former U.S. Secretary of State Colin Powell once said, “Leadership is solving problems.” But for jewelry retailers, finding store managers who are excellent leaders can prove problematic.Jewelers in particular often are tempted to reward their best sales associates with a promotion to management. And therein lies the rub: “Most awesome managers are not awesome salespeople,” says Shane Decker, a retail consultant for jewelry stores and president of Ex-Sell-Ence sales academy.Decker recalls a chain jewelry store that in the 1990s promoted all its top salespeople to positions in store man