Complementary contrast results from colours that are directly opposite each other on the colour wheel.  While this contrast is similar to warm-cool contrast, it is different in that in complementary contrast the colours must be of the same intensity.http://hominspire.com

This type of contrast has a sense of unity to it because the colours add up to the totality of light.  Complementary contrast often is very elegant and sophisticated. http://excitingwindows.com