The ornamental design for a ring, as shown and described.
1. Ring
1.1 : Perspective
1.2 : Front
1.3 : Back
1.4 : Right
1.5 : Left
1.6 : Top
1.7 : Bottom
In the representations of the design blurred lighter portions indicate disclaimed features for which protection is not being sought, whereas darker portions represent features for which protection is sought.