Three different ways are used to etch diamond {001} and {111} faces by oxidative methods: gas phase etching in dry oxygen, gas phase etching in a mixture of oxygen and water vapour, and liquid etching in molten potassium nitrate. The surface topography of the etched surfaces is compared with the theoretically predicted morphology. It appears that in most cases the experimental results are in contradiction to theory. These discrepancies are explained by the reactions between the diamond surfaces and the adsorbed oxygen, which are able either to stabilise or to destabilise the surfaces. Of these three methods, etching in molten potassium nitrate was found to be the best for revealing dislocations. (C) 2000 Elsevier Science S.A. All rights reserved.