Dark Blue vs Prussian Blue

How close are they?

ΔE 11.7, fair: the same colour family, but not a straight swap. Prussian Blue is a little lighter, warmer than Dark Blue.

Can I use Prussian Blue instead of Dark Blue?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Prussian Blue is a little lighter, warmer than Dark Blue.

Can I use Dark Blue instead of Prussian Blue?

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