[3] Many different recipes of Payne's grey have existed due to the fact that the shade is a composite colour.
The original mixture was made with Prussian blue, yellow ochre, and crimson lake in the late 18th century.
[3] A recipe listed in the 20th century, called for indigo instead of Prussian blue, and now it appears to be made by mixing ultramarine (natural or artificial) with a carbon-based black.
The reason why they are similar is because both colours are made of the same pigments of indigo, ochre, and ivory black in watercolour, but in different proportions.
Even though Payne's grey has a composition for acrylic paint, which uses a mixture of artificial ultramarine, ochre, and ivory black, its visual properties stay the same.