Wilhelm Ostwald's 1921 tone triangle for one yellow: the pure yellow at the left point, paler yellows stepping up toward white at top right, darker olive yellows stepping down toward dark gray at bottom right, grayed yellows between, and a column of four grays on the right edge; edges lettered a, e, i, n.

Concept · Foundations

Hue, Value and Saturation

Every color has three properties: hue, its color family (red, blue-green); value, how light or dark it is; and saturation, how strong or grayed it is.

Each can change while the others hold still. The chemist Wilhelm Ostwald's 1921 triangle starts from one yellow: mixed toward white it makes tints along the top edge, toward black shades along the bottom, and toward gray the tones between. All three usually also lower saturation.

Name a color by all three, such as a light, grayed blue-green, rather than by an object like sage.
Black shifts hue as well as value: stirred into yellow, it gives olive greens.

Image: Science History Institute Digital Collections · Public domain