If the seal on the jar is purple-black and dark, it generally indicates blood stasis, such as menstrual disorder, dysmenorrhea or insufficient blood supply to the heart. Of course, if the affected area is severely cold, purple and dark marks will also appear. If the impression lasts for several days, it often means that the course of the disease has been long and more treatment is needed. If there is a large area of black and purple imprint on the moving pot, it suggests that the area caused by cold is very large, so it should be treated symptomatically to drive away cold and evil spirits.