Infrared spectroscopy is an effective method to identify the substance and analyze the structures of molecular. Generally, the molecules and functional groups in gemstones display specific infrared absorption. According to the number, wave number, displacement, intensity of the infrared absorption spectrum, it helps analyze the infrared spectrum of a gem. We can identify the gem species and even distinguish gem subspecies through the infrared spectrum, separate gems from other imitations. The infrared spectrum plays an essential part in enhancement, treatment, and distinguishing natural gemstone from the synthetic gemstone. Meanwhile, the infrared spectrum provides some clues to identifying the origin of a gemstone.

1.Sample identification

2.Distinguish gem subspecies

3. Identification: natural or synthetic gems

4.Treatments identification

5.Enhancement identification

6. Identify synthetic gem method

Figure 1. Tsavorites and demantoids with similar appearance.

Figure 3. Infrared spectrums of garnets.