Which bodies show luster, and whose colour it takes
Rough surfaces give none; metals hold the body's colour, glass and jewels the light's
This leaf continues the treatment of luster with chapters 777 to 779. It teaches that opaque bodies with a dense, rough surface never produce luster, while dense bodies with a dense smooth surface carry luster wherever the surface can receive the angle of incidence of light and eye, so mirroring their surroundings that the plain lit tone is lost. Chapter 779 adds that luster generally takes the colour of the light rather than of the body, except in burnished gold, silver and metals, whose luster keeps the body's own colour, whereas the luster of leaves, glass and jewels borrows mostly the light's colour. The page is unbroken text with no drawing.
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Rough dense bodies never produce a highlight
Chapter 777 states that opaque bodies with a dense and rough surface never generate luster anywhere on their illuminated part. Chapter 778 adds that dense bodies with a dense smooth surface carry luster wherever the surface can receive the angle of incidence of light and eye, and mirror their surroundings so completely that the plain lit tone is no longer recognised.
Luster takes the colour of the light, not the body
Chapter 779 holds that on dense surfaces the luster partakes much more of the colour of the illuminating light than of the body itself. The luster of leaves, glass and jewels borrows little from the body where it arises and much from the light that strikes it.
Metals keep their own colour in the highlight
By contrast, chapter 779 notes that the luster of many shadowed bodies is entirely the colour of the lit body itself, as in burnished gold, silver and other metals and similar bodies. The painter must therefore judge each material's highlight by its own nature.