There has been considerable interest in the Electro-Optic community in utilizing diamond-turned optics for compact optical systems. The ability to generate complex, fast surfaces that far surpass the capability of glass substrate optics has proved invaluable in the design and development of automated test equipment. The current state-of-the-art diamond-turning process can introduce a variety of errors to the overall figure of the surface. The nature of these errors and the effect on surface quality are critical concerns for the system designer. To date, diamond-turned optics have been successfully used for both co-herent and incoherent applications in the mid to far Infrared (IR) spectrum where very good surface quality can be achieved. These applications range from laser resonator optics to telescopes. However, when the optics are used in the near IR to visible spectrum, surface quality becomes very critical. The same surface that may be exceptional for use in the mid to far IR spectrum may be totally unacceptable in the near IR to visible spectrum. In many applications, such as telescopes, involving the near IR to visible spectrum, system require-ments call for focusing incoherent radiation. However, there are also applications, such as laser performance in the far-field, where focusing coherent radiation is required and surface quality becomes an important system parameter. One method of determining surface quality of a diamond-turned optic is presented here, whereby the far-field diffraction pat-tern of a fast diamond-turned two mirror collimator, as an example, is observed for coherent radiation at 0.6328 microns, partially coherent radiation at 0.6328 microns, and coherent radiation at 1.0624 microns.