A description of the surface structures consisting of hexagonal (2\ifmmode\times\else\texttimes\fi{}2)-reconstructed domains of ad- atoms, which tile the (111) face of diamondlike crystals and have domain boundaries building up a continuous net of c(4\ifmmode\times\else\texttimes\fi{}2)-antiphase domain boundaries, is presented. Calculations of the structure factors of such honeycomb reconstructions show that not all of them account for the splitting of the half-order reflections observed in the diffraction pattern of the moderate-temperature phase of Ge(111). The relation between the splitting and the average domain radius of the honeycomb structures is deduced. Using the temperature dependence of the splitting measured by Phaneuf and Webb [Surf. Sci. 164, 167 (1985)], the average domain radius is found to vary almost linearly with temperature. The effect on the diffraction pattern of either the deformation compatible with a perfect honeycomb net of antiphase domain boundaries or the breaking of this net is discussed. Deformed structures are similar to those real-space images obtained with the scanning tunneling microscope on the stabilization at room temperature of the moderate-temperature phase of Ge(111) by means of Ga.