US D559723 S1
The ornamental design for a watch fastener, as shown and described.
FIG. 1 is a perspective view of our claimed design;
FIG. 2 is a side perspective thereof, with the opposite side being a mirror image;
FIG. 3 is a top view thereof; and,
FIG. 4 is a bottom view thereof.
The broken lines are for illustrative purposes only and form no part of the claimed design.