The ornamental design for a desktop apparatus for testing precious metal, as shown described.
FIG. 1 is a front perspective view of one embodiment showing our new design for a desktop apparatus for testing precious metal;
FIG. 2 is a top plan view depicting the desktop apparatus for testing precious metal shown in FIG. 1;
FIG. 3 is a bottom plan view depicting the desktop apparatus for testing precious metal shown in FIG. 1;
FIG. 4 is a front elevation view depicting the desktop apparatus for testing precious metal shown in FIG. 1;
FIG. 5 is a rear elevation view depicting the desktop apparatus for testing precious metal shown in FIG. 1; and,
FIG. 6 is a left side elevation view depicting the desktop apparatus for testing precious metal shown in FIG. 1, which has left and right side symmetry.