Anthropologists have exhaustively verified a universal set of eleven basic color terms shared by all cultures: white, black, red, green, yellow, blue, brown, purple, pink, orange, and gray.[i] Categories like these are not hierarchal,[ii] but all exist under the subheading of “color terms,” which itself should be considered above these colors in a sort of hierarchical rank. There are also “black” and “white”, which we roughly interpret to mean “dark” and “light,” and since there are only two of these, they can be considered in a separate category from colors. Let’s call these “shades.”
[i] Eastman, C. Anthropological Perspectives on Classification Systems. 5th ASIS SIG/CR Classification Research Workshop, 69-78. doi:10.7152/acro.v5i1.13777 Alexandria, VA, October 16, 1994
[ii] Eleanor Rosch, "Principles ofcategorization," in Cognition and Categorization, Eleanor Rosch and B. B. Lloyd, editors, Lawrence Erlbaum Associates, Hillsdale, New Jersey, pp. 27-48, 1978.