A color wheel or color circle is an abstract illustrative organization of color hues around a circle, which shows the relationships between primary colors, secondary colors, tertiary colors etc. Some sources use the terms color wheel and color circle interchangeably; however, one term or the other may be more prevalent in certain fields or certain versions as mentioned above. For instance, some reserve the term color wheel for mechanical rotating devices, such as color tops, filter wheels or the Newton disc. Others classify various color wheels as color disc, color chart, and color scale varieties. History In his book Opticks, Isaac Newton presented a color circle to illustrate the relations between these colors. The original color circle of Isaac Newton showed only the spectral hues and was provided to illustrate a rule for the color of mixtures of lights, that these could be approximately predicted from the center of gravity of the numbers of "rays" of each spectral color present (represented in his diagram by small circles). The divisions...