On Valentine's Day, Ann and Donald exchange permanent gifts. She gives him a tie clasp and he gives her a pair of genuine diamond earrings they saw together at Tiffany's. Ann is scared to wear them. When Don puts his foot down and insists she wear them on their evening of dinner and dancing, one of them indeed disappears. Don buys her a replacement earring and puts it in her apartment. Ann, not wanting to disappoint Dan, buys a replacement earring herself. (thetvdb.com)