A systematic comparative study on the natural diamonds, the natural diamonds after annealing and irradiation and synthetic diamonds prepared by chemical vapor deposition (CVD) or high pressure and high temperature (HTHP) are investigated by DiamondView combined with UV-Vis-NIR absorption spectra and Fourier transform infrared spectra. The results show that the fluorescence′s color of colorless or near-colorless natural diamond shows a single blue color with no phosphorescence, closure or misclosure ring-structural growth lines or irregular lines are existed in theirs corresponding fluorescence images. Some natural diamonds have blue fluorescence and greenish blue phosphorescence. Meanwhile, parts of natural diamonds have the characteristic with no fluorescence and no phosphorescence, most of CVD synthetic diamonds have the characteristics of fluorescence and phosphorescence. Therefore, it is not scientific to identify of natural and synthetic diamonds based on theirs phosphorescence. The fluorescence′s color of natural diamond treated by irradiation and heat treatment display the other color expect blue. After irradiated, diamonds show large variations in their fluorescence patterns, particularly in the fluorescence′s color. Furthermore, the fluorescence color show mixed-color because of the color center defect resulted from irradiation. It should point out that the instruments of UV-Vis-NIR spectrometer and DiamondViewTM are very powerful tool for studying irradiation in all sorts of diamonds until now. Unique fluorescence′s characteristics with parallel lamellar growth striations appear in the table and pavilion of the majority of CVD synthetic diamonds and are powerful evidences to identify CVD synthetic diamonds, which correlation with the preparative technique of chemical vapor deposition. Additionally, the DiamondViewTM images of CVD diamonds display light blue phosphorescent.