Abstract: A decorative optical display (20) utilizing a reflective diffraction grating (94) or a transmissive diffraction grating (304) and a plurality of polychromatic light sources (60) disposed around perimeter (106) of the reflective diffraction grating or perimeter (314) of the transmissive diffraction grating. The light sources are disposed so as to the illuminate the reflective or transmissive diffraction grating at an oblique angle (204) or (328), respectively. The oblique illumination of the reflective or transmissive diffraction grating prevents a viewer (200) from seeing undiffracted light rays (212) or (336) emanating from the light sources, which can detract from the appeal of the optical display pattern (250). The reflective or transmissive diffraction grating may be flat or curved and may be supported by a support member (90). Further, the reflective or transmissive diffraction grating may have either a single or multiple axes.