Selective polycrystalline diamond thin film has been grown on a silicon dioxide/silicon substrate using high pressure microwave plasma-assisted chemical vapor deposition from a gas mixture of methane and hydrogen at a substrate temperature of 950 degrees C. A simple process flow has been developed to fabricate diamond microstructures such as diamond beams and cantilever beams using surface micromachining and photolithography for the first time. Scanning electron and optical microscopy has been used to characterize the surface micromachined diamond microstructures.