Blending colors is a great way to create a different aesthetic appearance with either complimentary or contrasting colors. In this playground, a more natural appearance was achieved by blending green and brown colors, and the safety surfacing blends in better with the surroundings, 

For something where there might be a desire to make it look like water or the ocean, for which blue and green could be blended together. It doesn't have to be limited to two colors, either. One customer purchased the four colors without black, then installed the four colors in blotches throughout the safety zone. 

Other customers like to create a xeriscape with zones of colors to depict grass with green, pathways with brown, rivers with blue, and like one client did, maybe little patches of red near a small bridge that goes over the "river," to look like flowering plants.