Comparison of the optical spectrum of SN 1987A at 714 d (black) with synthetic spectra of the SN II model at 700 d with different assumptions on the dust properties (red). The observed spectrum has been corrected for redshift and reddening. The model spectra have been scaled to the SN 1987A distance. When included, the dust is chosen to be 0.1 μm silicate grains and located in the inner metal-rich ejecta. [See Sect. 7 for discussion.]