Polishing of {100} and {111} single crystal diamond through the use of   Chemical Mechanical Polishing
  Diamond is one of the hardest and most difficult to polish materials. In this paper, the polishing of {111} and {100} single crystal diamond surfaces by standard Chemical Mechanical Polishing, as used in the silicon industry, is demonstrated. A Logitech Tribo Chemical Mechanical Polishing system with Logitech SF1 Syton and a polyurethane/polyester polishing pad was used. A reduction in roughness from 0.92 to 0.23 nm root mean square (RMS) and 0.31 to 0.09 nm RMS for {100} and {111} samples respectively was observed. 
Evan L. H. Thomas, Soumen Mandal, Emmanuel B. Brousseau, Oliver A.   Williams
cond-mat.mtrl-sci