The Emerald of Killarney was a mystical object that carried a curse of bad luck, which explained why it was feared throughout the world. It usually casts the curse on someone if the person took it from its tomb in Ireland. If the emerald is passed from its current owner willingly to another, the curse will pass on. But if the jewel is stolen before the owner could pass it on, the curse will stay with them. Finn then admits that the Emerald is cursed, and Jackie tells Finn that he will take the curse back, if Finn, Chow and Ratso will leave Jackie alone.