The structure factor ratio between the theoretical aspherical model and the spherical IAM of the electron density in diamond is shown as blue dots. The black dotted curve is a guide to the eye, which in case of degenerate reflections shows the weighted average of the theoretical structure factors. It serves as the theoretical result, which the experimentally derived structure factors can be compared with. Note that the difference between the IAM and the aspherical model is at most a few percent. The structure factor ratio between the derived structure factors from PXRD and the IAM is shown in magenta with error bars as given in Fig. 6. The experimental structure factors were obtained by scaling the reference peak as outlined in §3.1. Only structure factors originating from Bragg reflections with an observed intensity larger than 5% of the background level have been included in the analysis.