Resembling a locket, Taköhl's Treasure Rings, available in platinum and14-karat gold, open up to reveal a smooth surface ideal for engraving. Designer Tammy Kohl, 43, started selling her jewelry more than 20 years ago to help pay her tuition at the University of Wisconsin at Milwaukee, ramping up production after the manager at Versace's Chicago store offered to buy her first ring for $1,200. An inscribed locket given to Kohl by her grandmother inspired the patented design of the Treasure Rings, which she sells in 16 customizable styles, including the newly released square-shaped Majestic band.