Diamond offers unique material advantages for the belief of micro- and nanomechanical resonators due to its high Young’s modulus, compatibility with harsh environments and superior thermal properties. At an equivalent time, the wide electronic bandgap of 5.45 eV makes diamond an appropriate material for integrated optics due to broadband transparency and therefore the absence of free-carrier absorption commonly encountered in silicon photonics. Here we cash in of both to engineer full-scale optomechanical circuits in diamond thin films. We show that polycrystalline diamond films fabricated by chemical vapour deposition provide a convenient wafer-scale substrate for the belief of high-quality nanophotonic devices. Previous studies in nanocrystalline diamond demonstrated nanomechanical resonators with frequencies up to 640 MHz. In this case, the mechanical material properties proved to be comparable to the ones found in bulk diamond, suggesting that polycrystalline diamond may be a suitable substitute for the realization of on-chip nanomechanical resonators. The micrometer-scale device size and high thermal impedance of the silica interface layer allow for significant thermal loading and continuous resonant wavelength tuning across a 450 pm range using a milliwatt-level optical pump. This diamond-on-demand integration technique paves the way for tunable devices coupled across large-scale photonic circuits. Diamond-based-optical-circuitry-latest-research are the summary of current state of understanding on a particular research topic. They analyze or discuss research previously published by scientist and academicians rather than reporting novel research results. Review article comes in the form of systematic reviews and literature reviews and are a form of secondary literature.