Pi disc, donut of striped jade from Myanmar.

Jade is the common name for two minerals that are used as gemstones: jadeite and nephrite. In the economic circuit, there is also fake jade. This is worth less than real jade. One can distinguish the two from each other because real jade changes color over a long period of time when it has been in contact with human skin for many years. Jade comes in many different colors: green, brown, black, or cloud white, from very light to very dark. Jade, like soapstone and chalcedony, has been carved and worked by the Chinese for thousands of years. Jade was originally used as a tool but became popular as a piece of jewelry during the Han dynasty. The only place where nephrite is found in China is in Sinkiang, around the city of Khotan. In Chinese culture, only processed jade is considered valuable. A lump of unprocessed jade is therefore of lesser value. In the Sanzijing, it is mentioned as a comparison with education: "If jade is not polished, it is not a precious thing." If a person does not learn, their life has no meaning, for they do not know the norms, values, and respect of life and will therefore never become talented" (玉不琢 不成器 人不學 不知義). Jade is seen as a valuable stone that wards off evil forces. If one wears a piece of jade on their body for a long time, for example, on a piece of red thread around the neck, one will see that the jade slowly changes color. During the 2008 Olympics in Beijing, the medals were adorned with jade.