The player is responsible for playing the correct golf ball. Every player should mark his ball.
If a player has reason to believe that a ball at rest is his ball and it is necessary to pick up the ball to identify it, he may do so without penalty and identify the ball.
Before picking up the ball, the player must announce his intention to do so to his opponent in the hole game or his counter or a competitor in the counting game and mark the position of the ball. He may then pick up and identify the ball, provided he gives his opponent, counter or competitor the opportunity to observe the pick-up and return. The ball may not be cleaned more than necessary for identification when it is picked up in accordance with Rule 12-2.
If the ball picked up is the player's ball and the player fails to follow this procedure in whole or in part, or picks up his ball for identification when this is not necessary, he incurs a penalty stroke.
If the ball picked up is the player's ball, he must put it back. If he fails to do so, he incurs the basic penalty for violation of Rule 12-2, but no further penalty under this rule.
Note: If the original position of the ball to be returned has been changed, see Rule 20-3b.
*PENALTY FOR BREACH OF RULE 12-2:
Hole play - Hole loss; Counting play - Two strokes
*If a player incurs the basic penalty for breach of Rule 12-2, no further penalty is incurred under this rule.
Status: 2018