Cobalt watercolor paints

Why do cobalt paints have different colors? Cobalt swatches Mixing swatches

Cobalt watercolor paints come in different colors because "cobalt" refers to the metal element in the pigment's chemical structure, not to a single color. The final hue depends on the other elements combined with cobalt during pigment production.
Some paints labeled as Cobalt Hue contain no real cobalt at all. Instead, they imitate the color using synthetic or non-toxic pigments