There is provided a method and apparatus for processing a diamond surface. The method comprises: i. locating a diamond material having a first surface and a second, opposite surface, in a holder, the holder located at the end of a positioning arm; ii. processing the first surface on a rotating wheel; iii. while the diamond material is in the holder, measuring an angle of the first surface relative to the second surface; iv. repeating steps (ii) and (iii) until a desired angle is achieved.