An illuminated device comprises a light source and an illumination plate, having a first face and a second face, separated by edges, and a diffusion cover, having an inner surface. The diffusion cover overlies the illumination plate and is shaped to form an enclosure defined by the inner surface and the first face. The light source delivers light into the illumination plate via the edges. The light undergoes scattering or primary diffusion within the plate, before emerging from the first face at shallow angles, into the enclosure. A reflective layer prevents light emerging from the second face. Within the enclosure, the light undergoes secondary diffusion to provide uniform illumination of the cover and a color, graphic or message superposed thereon.