The ornamental design for a diamondnecklace, substantially as shown and described.
FIG. 1 is a top plan view of a diamond necklace showing my new design
portions of the continuous neck chain being broken away for convenience of
illustration;
FIG. 2 is a bottom plan view thereof;
FIG. 3 is a side elevational view thereof; and
FIG. 4 is a sectional view as seen from the plane 4--4 in FIG. 3.