I've come across the concept of complementary colours where if a compound absorbs one wavelength then to the eye, it will appear as its complementary colour. Heres a chart of complementary colours: so for example if a compound absorbs violet radiation, the compound will appear yellow. In college I did an experiment involving the ferroin (an iron-phenanthroline complex) and determined that its maximum absorption occurs at 511 nm. This observation coincides with this complementary colour theory because 511 nm lands in the cyan region of the visible spectrum and ferroin is orange (cyans complementary colour). What I don't understand is how does this work when a compound has more than one significant visible absorption? What colour would it appear then? Is it determined by the compounds most intense absorption?