Metalness (PBR)
A PBR material property that tells the renderer whether a surface behaves like a metal (1) or a non-metal (0).
Metals and non-metals reflect differently
Metals reflect most of the light that hits them, and their reflections are tinted by the metal's colour. That is why gold reflections look golden. Non-metals such as gems, enamel and plastic reflect only a little untinted light at the surface, and the rest of their look comes from light entering the material.
Values for jewelry
- Gold, silver, platinum and other metals, metalness 1.
- Diamonds and gemstones, metalness 0, with transmission and IOR doing the work.
- Enamel, pearls and stones such as onyx, metalness 0.
- Values between 0 and 1, mainly for blending, such as dirt on metal. Real jewelry rarely needs them.
Common mistakes
Setting a gemstone to metallic makes it look like a coloured mirror ball. Setting gold to non-metallic makes it look like yellow plastic. If a material looks wrong in every environment, check metalness before anything else.
Base colour and metalness
For metals, the base colour sets the tint of the reflections, so it should be the metal's colour, such as a warm yellow for 18k gold. For non-metals, base colour is the body colour. Pair metalness with roughness to set the finish.