Abstract: Diamond film (DF), consisting of carbon atoms and with structure of diamond, posseses a series of special chemical, physical and optical properties, which is a kind of crystalline material synthesized by chemical vapor deposition method (CVD).Colourless and transparent diamond film is a hot topic of gemmological diamond materials and notable when people study cubic oxidation-zirconium.How to grow colourless and transparent diamond film on the cubic oxidation-zirconium is a new deceptive technology of diamond imitation.In this paper, authors takes a series of conventional gemmological testings and the results show that surface of the sample has dark blue film and its interior is clean with some conchoidal fracture at the edge.The density of the sample is 5.78~5.83g/cm³ and refractive index of unfilmed part is above 1.78, which is primarily identified as the synthetic cubic oxidation-zirconium.However, the surface of the sample has low hardness and is smooth, which is different from the structure of polycrystalline diamond film and aligning orientation of singlecrystal diamond film.Therefore, small angle X-ray diffraction spectrometer and infrared spectrometer are used in physical, chemical and spectroscopic testings to analyze the sample and determine the chemical composition of the surface film.X-ray diffraction analysis reveals that the surface film is amorphous phase and the result of X-ray photoelectron spectrometer shows that the film primarily consists of element C and F.Combining with the film literature, we can confirm that the film is fluorinated amorphous carbon (a-C:F) Films.Region during 950-1 250cm^-1of infrared spectra is analyzed by ORIGIN software of gaussian function.Six peaks are found, such as stretching vibration of CF (1 030, 1 068cm^-1), stretching vibration of CF₂ (1 090, 1 160, 1 220cm^-1), stretching vibration of CF₃ (980cm^-1), which confirms further that the surface film is a-C:F film.