Most of us are more familiar with the colors of the rainbow than the light and pigment colors. The rainbow has seven colors (including indigo or blue-violet as a color). In this diagram, being a mixture of blue and violet, indigo is not given a separate circle.
We are also familiar from water colors and transparent inks with mixing all colors from red, yellow and blue. Those are the colors of ink in most home printers. Red and yellow make orange. Yellow and blue make green. Blue and red make violet.
In this system, red, yellow and blue are the primary colors. Mixing them produces the secondary colors orange, green and violet. Mixing the secondary colors does not yield the primary colors but rather the earth colors. Green and violet make olive. Orange and green make citrine. Violet and orange make russet. Mixing the three earth colors yields black (or a brownish black).
This system is visually displayed in the Qabalistic Tree of Life.
Note that the supernals are the three non-colors: white, grey and black.
The next triad consists of the three primary colors, blue, red and yellow.
The next triad colors are generated by mixing the three primary colors. Blue and red mix to form violet. Note that the spheres with these three colors (4,5 and 9) form a big equalateral triangle. Blue and yellow make green. Note that these spheres form a smaller equilateral triangle (4,6 and 7). Red and yellow form orange – also a small equilateral triangle (5, 6 and 8).
Mixing the secondary colors yields the earth colors of sphere 10, Malkuth, the Kingdom. Mixing green and orange yields the citrine color at the top of sphere 10. Mixing green and violet gives the olive color on the right of sphere 10. Mixing orange and violet yields russet as on the left of sphere 10. Mixing all three – green, orange and violet – yields black pictured at the bottom of sphere 10.
This progression from non-colors to primary colors, mixed to form the secondary colors, mixed to form the earth colors, mixed to yield black yields much in meditation and other work upon the Tree of Life.