Before the following work many components are to grind and to polish, to finish. That takes time.

Process:

A wooden disc (boxwood) turns in the spindle of a lathe, which is greased and wetted with diamond powder (0-2), only a few. A spindle clamped on the slide rest remains able to move to and fro.
With polishing it is to turn and to move by hand, so the workpiece can be pushed gently against the boxwood disc. During this procedure also the slide rest is to move. After a short time one takes the workpiece with the spindle head back and checks the polishing of the screw head.
Of course everybody has to find the way to a fine polishing.
But important is the advice, take real diamond powder and never diamantine, or something else!