The tetradic color scheme or double complementary color scheme. This color scheme is the richest of all the schemes because it uses four colors arranged into two complementary color pairs. This scheme is hard to harmonize; if all four colors are used in equal amounts, the scheme may look unbalanced, so you should choose a color to be dominant or subdue the colors.
Pros: The tetradic scheme offers more color variety than any other scheme.
Cons: This scheme is the hardest scheme to balance.
1. If the scheme looks unbalanced, try to subdue one or more colors.
2. Avoid using pure colors in equal amounts.
I don’t actually have my own art work that I can think of that is in tetradic color scheme, but I will dig around and see what I can find soon.
It is the last tip of how to create color harmony on your illustration or color sketch, I hope this is useful.