Tetradic color schemes have a rectangular or quadratic relationship amongst the chosen colors. These schemes are quite lavish for now you have four colors to play around with but a little care must be taken in design to unite all of them together into a harmonious whole.
The split complementary tetrad (white and red rectangles in the above wheel form two examples) consists of two colors one space apart from each other and both their complements. In the white rectangle, the complements of red and orange are green and blue, so the scheme consists of red, orange, green and blue. These two pairs lie, naturally, on opposite sides of the wheel, one pair being warm and the other cool. Make one, either the warm or cool pair more dominant than the other. This can be done by using more of one in terms of area but also in other ways…. e.g pure, strident hues (they stand out) against subdued or grayed colors or using hue or value contrast.
The adjacent complementary (yellow rectangle in the wheel above) tetrad consists of two adjacent colors along with their complements. This gives the most harmonious results amongst the three tetradic schemes because of the colors lying next to each other but still gives some movement (some zing!) as compared to the analogous scheme because it includes colors lying on the opposite side of the wheel. In this painting “whispers”, I`ve used red, red-violet, green and yellow-green (though the red is a cool red, schminke magenta).
The square tetrad or the cross complementary tetrad (the small violet square in the color wheel) consists of four colors equidistant on the color wheel, each spaced two colors apart from each other. Again, these are two pairs of complements. This forms the most striking and dynamic of all schemes as the colors are, so to say, thrown as far apart as possible from each other. In this example, I`ve used red-orange, yellow, blue-green and violet.
Apart from these there are other color schemes like
Monochromatic scheme – This scheme uses only one hue in its different values i.e. in all its tints, tones and shades.
Achromatic scheme – An example would be artwork done in graphite. It is called achromatic because it is not in color. Adding slight hints of colors gives some variations to this theme.
Neutral scheme – consists of neutral or near neutral hues like browns, beiges, grays..