1. Preheat your oven into 450 degrees Fahrenheit
2. Place your marbles on a loaf pan and bake for 20 minutes
3. While you are waiting, prepare a bowl of cold water with ice in it
4. Once the marbles are baked, immediately put them in the cold water
This will crack the insides of the marbles, turning them into shiny marbles!
Warning: When you are cooling the baked marbles in the water, some may crack open.
Even if you do not have an oven in your house, you can always heat the marbles on the frying pan. When my mother was small, she made baked marbles using a frying pan.