The Rules of golf do not actually compel you to mark your golf ball, but there are very good reasons why it’s strongly advisable to do so…

With regard to marking your golf ball, The Rules of Golf simply state the following: “The responsibility for playing the correct ball rests with the player. Each player should put an identification mark on his ball.” (Rule 6-5 and Rule 12-2).

When I first started playing before the days of the Sharpie, no-one I played with did this, other than a few pros who used to put a series of tiny dents in the surface of a balata ball with the end of a tee-peg. We used to just rely on the brand, model and number for identification purposes. But was this enough? Well, yes, in most instances according to Decision 12-2/1 in the Decisions on the Rules of Golf book…

Identifying Ball by Brand, Model and Number Only

Q. In the area in which his ball presumably came to rest, a player finds a ball of the same brand, model and identification number as the ball he is playing. The player assumes it is his ball, even though it does not carry an identification mark as suggested in Rule 12-2, and plays it. Should the player be considered to have played a wrong ball?

A. No, unless (1) there is clear evidence that, because of the ball’s condition, it is not the player’s ball or (2) subsequently it is established that another ball of the same brand, model and identification number was lying in the area at the time the player played and either ball, from a condition standpoint, could be the player’s ball.

But before you get too complacent, what if you and a fellow-competitor are playing the same brand, model and number and despatch them to the same area – a long shot, admittedly, but it could happen. Now, according to Decision 27/10, it’s not such good news…

Player Unable to Distinguish His Ball from Another Ball

Q. A and B hit their tee shots into the same area. Both balls were found but, because A and B were playing identical balls and neither had put an identification mark on his ball, they could not determine which ball was A’s and which was B’s. What is the ruling?

A. Since neither player could identify a ball as his ball, both balls were lost – see Definition of “Lost Ball”. This incident underlines the advisability of the player putting an identification mark on his ball – see Rules 6-5 and 12-2.

The following situation, though, is more likely given that many players will be drawing from a sleeve of same-numbered balls out on the course – despatching a provisional to the same area as the original, which either bears no identification mark or the same one as the original. Indeed, I remember a fellow competitor doing just this in a Men’s Open 25 years ago, and neither of us knowing quite how to proceed. Well, the comprehensive Decision 27/11 pretty much covers off all potential eventualities…

Such artwork is not essential, but marking your ball rules out any scope for confusion

Such artwork is not essential, but marking your ball rules out any scope for confusion

Provisional Ball Not Distinguishable from Original Ball

Q. A player entitled to play a provisional ball from the tee plays it into the same area as his original ball. The balls have identical markings and the player cannot distinguish between them. Following are various situations and the solutions, which are based on equity (Rule 1-4), when the above circumstances exist and one or both of the balls are found within a search of five minutes:

Situation 1: One ball is found in a water hazard and the other ball is not found.
Solution 1: The ball that was found must be presumed to be the provisional ball.

Situation 2: Both balls are found in a water hazard.
Solution 2: As the player’s original ball is lost in the water hazard due to his inability to identify it (see analogous Decision 27/10), the player must proceed under Rule 26-1 with respect to the original ball (estimating the spot where the ball last crossed the margin of the hazard, if necessary – see Decision 26-1/17); his next stroke would be his third.

Situation 3: One ball is found in bounds and the other ball is lost or is found out of bounds.
Solution 3: The ball in bounds must be presumed to be the provisional ball.

Situation 4: Both balls are found in bounds, whether in a playable or an unplayable lie, and (1) one ball is in a water hazard and the other is not or (2) both balls lie through the green or in a bunker.
Solution 4: One could argue that both balls are lost. However, it would be inequitable to require the player to return to the tee, playing 5, when the player has found both balls but does not know which is the original and which the provisional. Accordingly, the player must select one of the balls, treat it as his provisional ball and abandon the other.

All of which should lead you to the conclusion that for the sake of avoiding any confusion or potentially costing yourself shots, you should carry a Sharpie or similar at all times, and always mark your golf ball with some form of identification mark, even if the Rules do not compel you to do so.

Oh, and if your provisional ball is the same brand, model and number as the original, mark it slightly differently in some way, so there can be no doubt which is which.