Wondering what happened to all those Preston’s Rocks commercials and billboards? After three years in business, local jeweler Reis-Nichols has given up on the spinoff, all-diamond concept. The store, in a funky building on 96th Street just west of I-69, closed in mid-January. The effort at a hip, youth-oriented jewelry store was a partnership of William Nichols and a Texas marketing firm. “The business wasn’t floundering,” Lori Roberts, a Reis-Nichols spokeswoman, said in an e-mail. “It was a clean and simple management decision to focus fully on our original Reis-Nichols business model.” The chain has stores in Castleton and Greenwood. What do you want to see in the old Preston’s building?