The color of cinnabar seal on the heart sutra

The color of cinnabar used to write the Heart Sutra is black. Because black can highlight the red color of cinnabar, making the text more vivid and beautiful. Therefore, the color of cinnabar used to write the Heart Sutra is black. Cinnabar is an important Chinese herbal medicine. Traditional Chinese medicine believes that it has the effects of enriching blood, stopping bleeding and regulating qi, and can be used to treat diseases.