Source : Webster's Revised Unabridged Dictionary (1913)

Pigmentation \Pig`men*ta"tion\, n. (Physiol.)
   A deposition, esp. an excessive deposition, of coloring
   matter; as, pigmentation of the liver.

Source : WordNet®

pigmentation
     n 1: the deposition of pigment in animals or plants or human
          beings
     2: coloration of living tissues by pigment [ant: {depigmentation}]