pigmentation
noun /ˌpɪɡmenˈteɪʃn/
  /ˌpɪɡmenˈteɪʃn/
[uncountable]- the presence of pigments in skin, hair, leaves, etc. that causes them to be a particular colour色素沉着;天然颜色 - The dark pigmentation of the skin gives protection in hot climates.皮肤的黑色色素沉着在炎热的气候下提供保护。 
 
- The dark pigmentation of the skin gives protection in hot climates.