Go on a map on survivail, save and exit. Then (you will need to remember or wright down cordiants) load your map you want the stuff on but this time on creative mode (try not to let the game save after it loaded). Mine around, when you find what you are looking for (write down the cordiants) turn off your game system. Load the same map on survivial mode and go to your cordiants and easy dimonds and other important things.