The ornamental design for metallic luster faces of a socket, as shown and described.
FIG. 1 is a perspective view of metallic luster faces of a socket showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left view thereof;
FIG. 5 is a top view thereof; and,
FIG. 6 is a bottom view thereof.
The broken lines depict portions of the metallic luster faces of a socket in which the design is embodied that are not considered part of the claimed design.