The ornamental design for a diamondlampstring, as shown and described.
FIG. 1 is a perspective view of a diamond lamp string showing my new design;
FIG. 2 is another perspective view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a right side elevational view thereof;
FIG. 6 is a left side elevational view thereof;
FIG. 7 is a top plan view thereof; and,
FIG. 8 is a bottom plan view thereof.
The diamond lamp string is shown with multiple symbolic breaks in its length. The dot-dash broken lines shown in the drawings are for illustrating the symbolic break only. The appearance of any portion of the article between the break lines forms no part of the claimed design. The dash-dash broken lines in the drawings depict portions of the diamond lamp string that form no part of the claimed design.