In the episode "Fairy Tale," Peter attempts to rescue Princess Gwen from the tower, he is wearing the locket on a chain. Later, the Princess asks for the locket back and Peter pulls the locket off the chain and he is still wearing the chain. When the guards arrive, Peter goes to fight them, but he is not wearing the chain. He is defeated and caught by the bad guys. One walks over to the Princess and threatens her/him. At this point, look at the left hand, the "magic" locket is back on the chain.