UVJ diagram in bins of stellar mass, for dust-free TNG100 fluxes (blue contours) and observational JWST/NIRCam data (with 1.8 ≤ z ≤ 2.2, grey contours), which are dust-attenuated. The dashed line indicates the demarcation between quiescent and star-forming galaxies from Williams et al. (2009) in their highest redshift bin (1 ≤ z ≤ 2). Here, and in all other figures, the contours are estimated from a two-dimensional (2D) kernel density estimate and enclose the densest 5, 25, 70, and 95 percent of the data. The TNG100 distributions are color-coded by their mean logarithmic specific star-formation rates in bins of V − J and U − V color. A strong correlation of sSFR with the dust-free UVJ colors of the simulated galaxies is evident. Dust attenuation must shift the simulated massive star-forming galaxies to redder colors in order to reproduce the observational distribution in the UVJ diagram.