Signs may be fabricated of any opaque material that does not have a glossy or reflective surface, except that glossy translucent material may be used:

(a)        in areas where the intent is to imitate or replace glass, as in transoms; or

(b)        for individual letters in internally lit illuminated signs.

Background colors for signs or common sign boards shall be limited to black, navy blue, dark green, maroon or bronze.