Abstract: Obsidian jewelry is at a good price after being given a unique cultural meaning by merchants, it became even more popular. Black obsidian is most easily imitated by artificial black glass. In terms of appearance, there is no difference between the two, and consumers cannot distinguish them. Samples of black obsidian without halo and its glass imitations were analyzed by conventional gemmological tests, infrared spectroscopy and X-ray fluorescence spectroscopy etc. The results showed that the infrared spectra of black obsidian and its black glass imitation samples, are significantly different, especially the transmission infrared spectra. At the same time, after summarizing a large amount of experimental phenomena, a simple and quick method for consumers to distinguish black glass from obsidian was found, which is observing the colour of the light source passing through the samples. When the colour of the light source changes to blue, purple, or red, the sample is black glass. If the colour of the light source is basically unchanged, the sample is more likely to be obsidian.