In the category of Wan Wen and jewelry, jadeite, agate, crystal and jade are not sold by the gram, which are non-standard products. The value of these items depends not only on the weight, but also on the color, texture, transparency, texture and other factors, and cannot be simply priced in grams. At the same time, the prices of these items are also affected by market supply and demand, brands, designers and other factors, so they are non-standard products.