A method of coating a rear glass substrate for an electrochromic reflective element includes providing a fixture having a recess and a masking element extending from a perimeter region of the recess over a portion of the recess. The masking element includes a disc portion and an arm portion extending between the disc portion and the perimeter region of the recess of the fixture. A rear glass substrate is positioned in the recess and the masking element extends over and is spaced from the surface of the glass substrate. The glass substrate surface is coated with a mirror reflector coating. The masking element is shaped such that the mirror reflector coating is deposited at the surface behind the arm portion but is substantially not deposited behind the disc portion so as to establish a window region through the mirror reflector coating at the glass substrate surface.