the present invention relates to a method of producing a diamond surface including the steps of providing an original diamond surface , subjecting the original diamond surface to plasma etching to remove at least 2 nm of material from the original surface and produce a plasma etched surface , the roughness r q of the plasma etched surface at the location of the etched surface where the greatest depth of material has been removed satisfying at least one of the following conditions : r q of the plasma etched surface is less than 1 . 5 times the roughness of r q of the original surface , or r q of the plasma etched surface is less than 1 nm .