. . "Third surface coating 636 may comprise an environmentally stable metallic layer or material, such as chromium or rhodium or ruthenium or platinum or the like, or a stack of, for example, of chromium/ruthenium or chromium/rhodium or chromium/platinum or the like, and thus provides an environmentally stable or robust wraparound coating at the perimeter region of the front surface 614 a of the rear s" . . . . . .