Check your ball. A matching brand is not enough.
Plain-language guide · Rule 6.3c. Use the current official text and your round’s Local Rules for a ruling.
What to know
The general penalty applies: loss of hole in match play or two penalty strokes in stroke play. In stroke play, correct the mistake in time.
On the course
Stop when you discover the error. Get help applying the correction before starting the next hole; do not continue with the wrong ball.