Chipped edges around the fixing holes in a mirror are often the result of not centralizing the screw when securing the mirror to a wall. To disguise the edges, fit a decorative rosette and dome-headed screw to cover the damage. Rosettes are manufactured with a chromium-plated finish, in plain white silver and in various colours.
Place a washer behind the mirror and fit a rubber grommet in the hole. Place the rosette over the hole and fit the screw through it, the grommet and the washer into a wall plug. Screw the dome-head cap into the screw head.