I claim the ornamental design for a necklace, as shown and described.
FIG. 1 is a top view of a necklace according to my new design;
FIG. 2 is a bottom side view of the necklace shown in FIG. 1;
FIG. 3 is a right side view of the necklace shown in FIG. 1;
FIG. 4 is a left side view of the necklace shown in FIG. 1;
FIG. 5 is a front side view of the necklace shown in FIG. 1;
FIG. 6 is a rear side view of the necklace shown in FIG. 1; and,
FIG. 7 is a top front perspective view of the necklace shown in FIG. 1.
The ornamental design which is claimed is shown in solid lines in the drawings. The broken lines in the drawings represent stitching which forms part of the claimed design.