5-3. Ball Unfit for Play
A ball is unfit for play if it is visibly cut, cracked or out of shape. A ball is not unfit for play solely because mud or other materials adhere to it, its surface is scratched or scraped or its paint is damaged or discolored.
If a player has reason to believe his ball has become unfit for play during play of the hole being played, he may lift the ball, without penalty, to determine whether it is unfit.
If it is determined that the ball has become unfit for play during play of the hole being played, the player may substitute another ball, placing it on the spot where the original ball lay. Otherwise, the original ball must be replaced.
*Penalty for Breach of Rule 5-3:
Match play - Loss of hole; Stroke play - Two strokes.
