The ornamental design for a surfaceornamentation for a gemstone, as shown and described.
FIG. 1 is a front elevational view of a surface ornamentation for a gemstone as applied on a gemstone, showing our new design. a rear elevational view and a side elevational view are identical to the front elevational view.
FIG. 2 is a bottom plan view of the gemstone with the surface ornamentation for a gemstone shown in FIG. 1; and,
FIG. 3 is a top plan view of the gemstone on which is applied the surface ornamentation for a gemstone shown in FIG. 1.
The broken lines in FIGS. 1-3 depict environmental features of the gemstone and form no part of the claimed design. The hatch pattern sections shown in FIGS. 1 and 2 indicate diffractive, etched elements of the design.