A lighting system comprising: a light source ; and a chromatic reflective unit wherein the chromatic reflective unit comprises a reflective layer, and a chromatic diffusing layer having a back side provided at the reflective layer and a front side for being illuminated by incident light from the light source , wherein the chromatic diffusing layer comprises a plurality of nanoparticles embedded in a matrix , and the chromatic reflective unit is 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, wherein said nanoparticles have an average size d in the range 10nm≤d≤240nm, the ratio between the blue and red scattering optical densities Log[R ]/Log[R ] of the chromatic reflective unit falls in the range 5≥γ≥2.5, where R(λ) is the monochromatic normalized specular reflectance of the chromatic reflective unit, which is the ratio between the specular reflectance of the chromatic reflective unit and the specular reflectance of a reference sample identical to the chromatic reflective unit except for the fact that the chromatic diffusing layer does not contain nanoparticles with the size d in the range 10nm ≤d≤240nm, and along the direction normal to the reflective layer, the number N of nanoparticles per unit area is given by N ≥ N min = 2.07 × 10 − 29 D 6 m 2 + 2 m 2 − 1 2 meters − 2 and N ≤ N max = 1.21 × 10 − 27 D 6 m 2 + 2 m 2 − 1 2 meters − 2 , D being the effective particle diameter given in meters, and wherein the chromatic reflective unit is shaped as a rotational paraboloid or a portion of a rotational paraboloid, and the light source is positioned close to or at the paraboloid focal position. a light source ; and a chromatic reflective unit wherein the chromatic reflective unit comprises a reflective layer, and a chromatic diffusing layer having a back side provided at the reflective layer and a front side for being illuminated by incident light from the light source , wherein the chromatic diffusing layer comprises a plurality of nanoparticles embedded in a matrix , and the chromatic reflective unit is 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, wherein said nanoparticles have an average size d in the range 10nm≤d≤240nm, the ratio between the blue and red scattering optical densities Log[R ]/Log[R ] of the chromatic reflective unit falls in the range 5≥γ≥2.5, where R(λ) is the monochromatic normalized specular reflectance of the chromatic reflective unit, which is the ratio between the specular reflectance of the chromatic reflective unit and the specular reflectance of a reference sample identical to the chromatic reflective unit except for the fact that the chromatic diffusing layer does not contain nanoparticles with the size d in the range 10nm ≤d≤240nm, and along the direction normal to the reflective layer, the number N of nanoparticles per unit area is given by N ≥ N min = 2.07 × 10 − 29 D 6 m 2 + 2 m 2 − 1 2 meters − 2 and N ≤ N max = 1.21 × 10 − 27 D 6 m 2 + 2 m 2 − 1 2 meters − 2 , D being the effective particle diameter given in meters, and wherein the chromatic reflective unit is shaped as a rotational paraboloid or a portion of a rotational paraboloid, and the light source is positioned close to or at the paraboloid focal position. <EOS>