A direct comparison between two complete intensity datasets, collected on the same sample loaded in two identical diamond-anvil pressure cells equipped, respectively, with beryllium and diamond-backing plates was performed. The results clearly demonstrate that the use of diamond-backing plates significantly improves the quality of crystal structure data. There is a decrease in the internal R factor for averaging, structure refinement agreement factors, and in the errors and uncertainties of the atomic coordinates, atomic displacement parameters, and individual bond lengths. (C) 2011 American Institute of Physics. [doi:10.1063/1.3590776]