>"In the 1960s, Pekka Pyykkö, now at University of Helsinki, Finland, discovered that gold’s colour was the result of relativistic effects. He showed that the l

>"In the 1960s, Pekka Pyykkö, now at University of Helsinki, Finland, discovered that gold’s colour was the result of relativistic effects. He showed that the lower energy levels of the 6s orbital of gold means that the energy required to excite an electron from the 5d band lies in the visible rather than UV range of light. This means that gold absorbs blue light, while reflecting yellow and red light, and it is this that gives the metal its characteristic hue."