A reliable means of removing surface layers of diamond is of significant importance for microelectronics as well as for other applications such as polishing of the diamond surface. Preliminary studies using reactive ion etching with O2 and H2 showed etching rates of the order of 560 Å/min for thin carbon films and 350 Å/min for natural type II-A diamonds using 300 eV oxygen ions. Addition of a substantial percentage of Ar to oxygen in the reaction chamber did not affect the etching rate.