Dark Prussian Blue vs Royal Purple

How close are they?

ΔE 9.8, close: similar, with a visible difference side by side. Royal Purple is a little lighter, more saturated, warmer than Dark Prussian Blue.

Can I use Royal Purple instead of Dark Prussian Blue?

Usually, if you are not matching paint already on the model. Close match (ΔE 10). Royal Purple is a little lighter, more saturated, warmer than Dark Prussian Blue.

Can I use Dark Prussian Blue instead of Royal Purple?

The same difference applies the other way round: Dark Prussian Blue is a little darker, more muted, cooler.

ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.