Various 4−50 nm in size diamond nanoparticles prepared by different synthesis methods and their fluorinated derivatives were studied by NEXAFS, solid state NMR and FTIR spectroscopy. C 1s and F 1s NEXAFS spectra of as-prepared and fluorinated nanodiamonds (NDs and F-NDs) were analyzed based on a comparison with the known ones of reference compounds (graphitized carbon nanodiscs, phenol and amino acid molecules, graphite oxide and monofluoride). It has been found that all the studied diamond nanoparticles have crystalline diamond cores and their surfaces are covered with graphite-like carbon clusters. These clusters are partially amorphized and oxidized with the formation of functional groups C−OH, C=O, or O=C−OH and the properties of these surface shells depend on the synthesis method of nanodiamonds. The fluorination of diamond nanoparticles has a purely superficial character; it almost completely cleans the NDs particles from carbon clusters and saturates dangling bonds on the surface of the diamond nanoparticle