The ornamental design for a necklace, as shown and described.
FIG. 1 is a front view of a necklace of the present design;
FIG. 2 is a rear view thereof;
FIG. 3 is a right side view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a top view thereof;
FIG. 6 is a bottom view thereof;
FIG. 7 is a front perspective view thereof; and,
FIG. 8 is a rear perspective view thereof.
The chain of the necklace is understood to have the appearance shown in FIG. 1. The chain may be interpreted as being shown in slightly different positions in FIGS. 2-8. In FIGS. 1, 2 and 8, the clasp of the chain is shown in an upright position, where in FIGS. 3-7, the clasp is shown in a downward position.