The reason why cinnabar is getting darker and darker is that mercury sulfide in cinnabar reacts with light and chloride ions to produce mercury. Cinnabar is actually an oxide of mercury. If cinnabar is exposed to the sweat secreted by human body for a long time, it will also react with the acid and alkali in the sweat, and then the color will become darker and darker. The color of cinnabar is getting darker and darker, which may be due to long-term exposure to air. Mercury sulfide in cinnabar reacts chemically with light and chloride ions to produce mercury. At this time, cinnabar will get darker and darker. In addition, cinnabar is actually an oxide of mercury. If cinnabar is exposed to a large amount of sweat secreted by human body for a long time, a certain chemical reaction will occur, and cinnabar will turn black. In fact, it is normal for cinnabar to get darker and darker. This situation can show that cinnabar is real. If you want to clean the blackened substance, it is recommended to send cinnabar to a jewelry store for professional cleaning.