What does good surface quality mean?

This is an English reading overview of the Chinese article, rather than a complete translation. The Chinese source has been updated since this overview was prepared; consult the original for the latest details.

The central idea

Surface quality is not a fixed colour or a separate skin layer. It describes the shell surface’s condition, fineness, handling response, colour development and stability. A white, pink or shiny fresh walnut is not automatically good. Look for natural colour transitions and a lasting warm lustre, supported by the underlying shell. Seek a natural, fine and stable surface rather than harsh brightness. Consider whether the texture and colour transitions are convincing and whether the shell supports gradual handling changes. A photograph under attractive lighting cannot establish every aspect of the surface’s condition or future behaviour.