A method for assembling a vehicular interior prismatic rearview mirror assembly includes providing a glass mirror substrate. The rear surface of the glass mirror substrate is coated with a reflector coating, and a protective coating is disposed over the reflector coating. A rear perimeter edge region of the glass mirror substrate is chamfered so that an angled surface is disposed between the rear surface and the perimeter edge. The reflector coating and the protective coating are disposed at the rear surface where the angled surface meets the rear surface. An encapsulant is disposed about a perimeter region of the rear surface so as to encompass and overlay the reflector coating and the protective coating at the rear surface and so as to encompass and overlay a portion of the angled surface, with no part of the encapsulant being disposed at the forward rounded perimeter region.