In this paper, experimental data are presented on the synthesis and properties of nanocrystalline diamond (NCD) films grown by a dc plasma CVD technique from various gas mixtures (CH4-H2, CH4-H2-Ar, CH4-Ar, CH4-H2-N2, CH4-Ar- N2). The interrelation between the CVD conditions, the film microstructure and film properties is established using Raman spectroscopy, XRD, XPS, AES, SEM, TEM, AFM/STM, spectroscopic ellipsometry and optical transmission spectroscopy techniques. Experimental methods for laser assisted fabrication of ultrathin and highly smooth NCD films are described. Effects of the deposition parameters (substrate temperature, CH4 content, addition of Ar gas to CH/H2 gas mixtures) on the grain size, surface roughness and optical properties of NCD films are discussed. Results of nitrogen doping of nanocrystalline diamond films are presented and discussed.