In an aspect, an illumination system (100) includes a light source (102) configured to generate a light beam (103), and a chromatic reflective unit (1) for being illuminated by the light beam (103). The chromatic reflective unit (1) includes a plurality of non-coplanar reflective surface sections (3′), and a chromatic diffusing layer (5) includes a plurality of nanoparticles (37) embedded in a matrix (39). The chromatic diffusing layer (5) is provided upstream of the plurality of reflective surface sections (3′) such that at least a portion of the light beam (103) passes through the chromatic diffusing layer (5) before and after being reflected by the plurality of non-coplanar reflective surface sections (3′). Chromatic diffusing layer (5) is further configured to provide for a specular reflectance that is larger in the red than in the blue and for a diffuse reflectance that is larger in the blue than in the red.