Below is a photograph of a color wheel marketed by The Color Wheel Company, Philomath, Oregon, www.colorwheelco.com . It is a useful tool for paint and pigment mixing. It includes features from both the Munsell and Ostwald color systems and uses the color characteristics hue, saturation and brightness. It also has some of the characteristics of the Newton Color Circle.
Below is a picture of the opposite side of the wheel. It gives further guidance about strategies for mixing paint colors.
The MUNSELL system is a collection of color samples for comparison, with adjacent samples based upon equal perceived differences in color.