The above illustration is a reduced copy of an actual Grumbacher Color Wheel. This device allows you to create new colors by dialing up a color on the outer ring. The inner white ring has windows that let you see the new color you created. You can see what happens when you add red, white, black, blue, or yellow to any of the 12 primary, secondary, or intermediate colors on the outer ring. This is a useful tool if you plan to work with deeper colors.
Artists use this tool to help them see what will happen when they blend different paints together on a canvas. You can use it to help see what will happen with certain colors as you squirt different types of pigments into the can. The back of the color wheel also has a helpful complimentary harmony guide. It shows what colors go well with other colors in an overall color scheme.
You can get this color wheel for less than $10. It is usually sold in any art supply store where artists buy brushes, paints, and canvases. You can also contact M. Grumbacher Inc.