A fold mirror for a projection display system is designed to lessen a perceived variation in white color balance of light reflected across the mirror wherein the white light is comprised of sub-beams of orthogonal polarization states. The mirror comprises a metal reflective layer and a plurality of optically transparent layers, wherein thicknesses and materials of the optically transparent layers are such that wavelength-averaged reflectance for p-polarized incident green light varies by less than 1%, wavelength-averaged reflectance for s-polarized blue light varies by less than 1.5%, and wavelength-averaged reflectance for s-polarized red light varies by about 4% over a range of angles of incidence between 0 and 65 degrees.