
In the image here of one of my monoprints, its possible to see several shades of pink, green, blue, orange, purple as well as a purple / brown colour. However the printing process only uses 3 colours (based on magenta, cobal t blue and cadmium yellow) - plus a partial under layer of cream (white and a touch of raw sienna).
All the colours you see in the print are created by the layering process on white paper, with the final colours created by either 1, 2, 3 or 4 layers of colour.
For example, the deeper blue is just one layer of blue on the white paper, the less intense blue is blue printed on cream, the deep purple is blue printed on magenta, and the brown is cream + magenta + blue + yellow. The greens are achieved by printing yellow over blue, with and without the cream under layer.
The final colours will vary according to the initial colours used, the number of layers, as well as the transparency of the inks. There are of course endless combinations!