Land of the Lost Jewels (1950)

Two children are fishing when they catch a talking fish named Red Lantern. He takes them underwater with him to the Land of the Lost, where missing items can be found again. They meet King Find All, a walrus, and a singing cricket (Hoppy-Go-Lucky) that used to be the girl's pin. He's deemed to be a special jewel (since he's made of emerald) and is brought to the jewel storage room, despite his wishes to be in the Land of the Toys. He runs away from Queen Tiara's guards, but is caught, and when they test him for authenticity they find he is only a fake diamond, after which he is allowed to live in the Land of the Toys after all. The children return to the surface and say goodbye to Red Lantern.