Simulated UVJ diagrams for galaxies within seven massive halos in DIANOGA PC regions at z = 2.2, within a 700 kpc aperture, produced with SKIRT-9. Intrinsic colors are connected to attenuated colors by gray arrows that end with star symbols color coded according to the sSFRs of galaxies. The left panel shows the diagram obtained by tracing dust in the diffuse ISM through a fixed dust-to-metal ratio. The right panel shows the diagram produced with the model for MCs described in Sect. 2.3. Typical cuts adopted in UVJ diagrams to separate quenched and star-forming galaxies (Williams et al. 2009; Whitaker et al. 2011, 2012; Muzzin et al. 2013) are shown as black lines, while the red line defines a custom-defined boundary to separate these populations in the DIANOGA simulations. The colored arrows show the reddening vectors for typical attenuation laws (Allen 1976; Prevot et al. 1984; Bouchet et al. 1985; Calzetti et al. 2000).