The ornamental design for a ring, as shown and described.
FIG. 1 is a perspective view illustrating the bottom and left side of a ring shown in an open condition;
FIG. 2 is a perspective view illustrating the top and right side of the ring in a closed position;
FIG. 3 is a left side view of the ring in an open condition;
FIG. 4 is a left side view of the ring in a closed position; and,
FIG. 5 is a bottom view of the ring in a closed position.
The broken line showing of the surface ornamentation on the clasp portions and strap of the ring is for illustrative purposes only and forms no part of the claimed design.