The identification of fractographic features, such as the mirror–mist boundary, is central in the fractographic analysis of silicate glasses and other brittle materials. Although phase-field simulations have been previously applied to unstable cracks propagating in amorphous brittle materials, limited efforts have been made to establish the formation of fractographic features. This work proposes two distinct approaches to predict the formation of the mirror–mist boundary in soda–lime glass. Glass beams with embedded corner elliptical notches loaded in bending were considered, and unstable crack propagation was simulated in phase-field. In one approach, the ‘mist’ was expected to form when the crack–front’s speed reached a critical threshold. In the second approach, the thickness of the damaged zone predicted by phase-field was tracked and correlated to the formation of the fractographic features. For the two proposed methods, both the shapes of the estimated mirror–mist boundaries and the magnitudes of the mirror radii were found to be in good agreement with experimental observations gathered from soda–lime glass beams fractured in bending.