The “type” of diamond had been developed and trended to perfect in last century. The spectral classification depends on ultraviolet visible near infrared spectrum (UV-Vis-NIR) and mid-infrared spectrum (MIR), mainly relates to nitrogen and boron impurity element. The structure models of nitrogen and boron in each type of diamond have tended to be more plausibility, but an enormous number of lattice defects even related to nitrogen are huge challenge for future work to reach a better understanding. This is an impenetrable wall on the way to explore new application areas for diamond. This article compiles some absorption characteristics in the spectra ranged from ultraviolet, visible light to infrared region. Especially the diamond classification system has been summarized completely. Furthermore, some absorbing features detected in the ultraviolet-visible and infrared spectral lines (UV-Vis-MIR) have been come up with a plausible explanation and/or established somewhat more reasonable structure models. It is very referential collecting these spectral characteristics and their corresponding theoretical models for further research and apply diamond materials.