Well, it's not "supposed" to happen but it CAN if the circumstances are just right. Any sort of crack or irregularity could affect the overall integrity of the ball and there are a few table manufacturers out there that can cause cracks in balls. I noticed with Kim Steels (sp?), the screws holding the pockets in place weren't recessed enough and would actually chip the balls over time. Anything can happen to them after that. I doubt you're ever going to see someone crack a cueball on a Brunswick or Diamond table.