Pay attention to the color of Yaozhu when buying. The surface is golden yellow, and when it is broken, it is golden inside, or slightly brown is a sign of freshness; There is a thin layer of white powder on the surface, but it has been air-dried for a long time. This kind of yaozhu can be used for soup, but it tastes far less fresh when used for cooking. Observing the surface is also a "homework" that must be done when buying a jade column. It is best to pick the surface intact to buy it.