In the 60s fried marbles were all the rage in the US. These days we no longer use a gas stove but simply add marbles to a baking tray. ;)
Set your oven to 230 degrees celcius and leave the marbles in for about 20 minutes. While they are happily baking away prepare them for the shock of being submerged into icy water: a bowl of cold water with icecubes added for good measure.
The marbles will crackle inside but keep their glossy sleak surface. Magic!
As soon as I have made some sparkly goodies from this I'll add pictures. :)