Kenan's parents are getting ready to celebrate their 17th wedding anniversary. Roger really wants to go all out to impress Sheryl, so he visits an old friend who owns a jewelry store. When Roger is unable to decide which cubic zirconium he wants, Nate--the store owner--lets him take the stones home to think it over. In the meantime, Kenan and Kel are watching ""America's Criminals"" and see a diamond thief who looks exactly like Kenan's father. Later they find the zirconium that Roger brought home and conclude that he is the thief. They get themselves into an even bigger predicament when they try to return the ""diamonds"" to the jewelry store.