The ornamental design for a surfaceornamentation for a scale, as shown and described.
FIG. 1 is a perspective view of a surface ornamentation for a scale, showing my new design; and,
FIG. 2 is a top plan view thereof.
The dash-dash broken lines showing scale depict environmental subject matter that forms no part of the claimed design, while the dash-dot-dot-dash broken line represents the bounds of the claimed design.