Tertiary color if they exist at all, though indigo and scarlet are standard for blue–violet and red–vermilion. In another sense, a tertiary color is obtained by mixing secondary-colored pigments. These three colors are russet (orange–purple), slate (purple–green), and citron (green–orange), with the corresponding three quaternary colors plum (russet–slate), sage (slate–citron), buff (citron–russet) (with olive sometimes used for either slate or citron). Beyond that are shades of grey (blue grey and brown greys), which approach but never quite reach black. The RYB color terminology outlined above and in the color samples shown below is ultimately derived from the 1835 book "Chromatography", an analysis
Shades of red in the diagram located at the bottom of the following website offering tintbooks for CMYK printing: . The purpose of the CMYK color system is to provide the maximum possible gamut of colors capable of being reproduced in printing. Psychedelic art made people used to brighter colors of red, and pigment colors or colored pencils called "true red" are produced by mixing pigment red with a tiny amount of white. The result approximates (with much less brightness that is possible on a computer screen) the electric red shown above. The color defined as "red" in the NCS or Natural Color