Synthetic diamonds possess excellent properties, including unparalleled hardness, thermal conductivity, and wear resistance, making them ideal for use as cutting tools in precision machining. Therefore, the quality and properties of synthetic diamonds are essential for their application in this field. This chapter explores the synthesis of diamonds, examining the processes and properties that make synthetic diamonds suitable for precision machining applications. Additionally, this chapter delves into the cutting performance of diamond tools, covering aspects from selection and fabrication to their actual use in ultra-precision machining.