Simulation of the overall SED of a 5000 K RCB star with a known episode of strong dust production of 10⁻⁸ M_⊙ at t = 0. The models were made using the 3D Monte Carlo radiative transfer code Mocassin (Ercolano et al. 2005) with a homogeneous distribution of amorphous carbon dust with the size distribution of Cardelli et al. (1989). The stellar radius is 100 R_⊙. The seven dots that define the dust shell SED correspond to the 2MASS and WISE passbands. The J-band luminosity of the one-month-old dust shell model is lower than the luminosity of the photosphere blackbody due to the extinction effect. It corresponds to the characteristic RCB star photometric declines, here of 1.2 mag in the J band.