The applications of composite materials based on carbon fiber reinforced plastic (CFRP) have been increasing considerably in aerospace industries, because of their good physical and mechanical characteristics. It is necessary to develop new manufacturing process and production techniques to ensure good surface quality of the components. As a result of this manufacturing scenario, it is necessary to study the machining process. This study reports practical experiments in turning, to study the performance of Poly Crystalline Diamond (PCD) inserts of two different grades. The results show that diamond tools are suitable for use in finish turning. The tests were carried out with PCD inserts at various cutting speeds on a medium duty lathe of spindle power 2KW. In the optimization method, turning was done by two different grades (PCD 1300, PCD 1500) for 30 seconds duration for each trial at different cutting conditions by using design of experiments. Parameters such as power consumed by main spindle, surface roughness were measured. Graphs were drawn to analyze the performance of two different grades on various parameters. Finally, it is concluded that the PCD 1500 grade is superior in all aspects.