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
Primary color of light (i.e., the spectral power distribution) reflected from illuminated surfaces coated in paint mixes, slurries of pigment particles, is not well approximated by a subtractive or additive mixing model. Color predictions that incorporate light scattering effects of pigment particles and paint layer thickness require approaches based on the Kubelka–Munk equations. Even such approaches cannot predict the color of paint mixtures precisely since small variances in particle size distribution, impurity concentrations etc. can be difficult to measure but impart perceptible effects on the way light is reflected from the paint. Artists typically rely on mixing experience and "recipes" to mix