Mix equal parts of cyan, magenta, and yellow pigment
Add a small amount of black pigment if needed to deepen the shade
For paint, combine ultramarine blue, burnt umber, and a touch of red
For food coloring, use black gel coloring or mix red, blue, and green in very small amounts
For dye, use a black fabric dye designed for the material
For digital color, set RGB to 0, 0, 0 or hex #000000
Adjust with tiny amounts of each color until the result is fully black