The plain ones are generally thrown flat and smooth, and the "flat" signifies "peace and quiet". There is nothing carved on it, which means "no word", and it harmonizes with "nothing", which means "nothing". Combined together, it means "peace and no matter", which is usually referred to as "peace sign".
Pregnant women and people with kidney failure should not use vermilion. Vermilion sand should not be burned with fire, as it will react chemically when exposed to heat, releasing toxic substances such as mercury and increasing toxicity.
When wearing vermilion sand jewelry, try not to use your mouth to directly touch the sand, basically it will not be poisoned, in fact, vermilion sand is not harmful to the human body as long as it does not become liquid or gaseous, or physical contact with vermilion sand only if the skin is not allergic to vermilion sand, you can also often wear vermilion sand jewelry.
Avoid chemicals and do not wear while bathing or sleeping. Avoid heat, scratching and impact.