Edit, rules added ...
Rule 20-1 says
If a ball or ball-marker is accidentally moved in the process of lifting the ball under a Rule or marking its position, the ball or ball-marker must be replaced. There is no penalty, provided the movement of the ball or ball-marker is directly attributable to the specific act of marking the position of or lifting the ball. Otherwise, the player incurs a penalty of one stroke under this Rule or Rule 18-2a.
Decision 20-1/6 Ball-Marker Moved Accidentally by Player in Process of Marking Position of Ball says
Q. A player marked the position of his ball with a coin, lifted the ball and pressed down the coin with the sole of his putter. He walked to the edge of the green and then noticed that the coin had stuck to the sole of the putter. What is the ruling?
A. In this case, the movement of the ball-marker was directly attributable to the specific act of marking the position of the ball.
Accordingly, no penalty is incurred and the ball or the ballmarker must be replaced. If the spot where the ball or the ballmarker lay is not known, it must be placed as near as possible to where it lay but not nearer the hole (Rule 20-3c).
