In this article the authors have studied the smoothing of diamond chips by irradiating them with 1 keV Ar ion beam at ion incident angles of 0°, 30°, 45°, 60°, and 80° with ion doses from 3.4×1018 to 6.8×1018 ions/cm2. They found that using ion dose of 6.8×1018 ions/cm2 at incident angles from 0° to 45°, the unprocessed surface (rms=0.14–1.2 nm) turned into ultrasmooth processed surface (rms=0.1 nm). Their results also confirmed the formation of ripples on diamond surface when the surface was irradiated with 1 keV Ar+ ion at incident angles of 60°–80°. They have also discussed the mechanism of smoothing and roughening of the surface by employing Bradley and Harper model and equations. These studies led to the understanding of the role of induced viscous flow in the smoothing process. Therefore, by choosing right conditions, 1.0 keV Ar+ ion beam machining can be employed to make diamond tools with nanofinished surface without any ripple effect.