  We investigate the correlation between surface roughness and corresponding
$T_2$ times of nearsurface nitrogen-vacancy centers (~7 nm/ 5 keV implantation
energy) in diamond. For this purpose we compare five different polishing
techniques, including both purely mechanical as well as chemical mechanical
approaches, two different substrate sources (Diam2tec and Element Six) and two
different surface terminations (O- and H-termination) during nitrogen-vacancy
forming. All coherence times are measured and compared before and after an
oxygen surface treatment at 520 {\deg}C. We find that the coherence times of
shallow nitrogen-vacancy centers are surprisingly independent of surface
roughness.
