Naggaroth Night vs Deep Blue

How close are they?

ΔE 9.2, close: similar, with a visible difference side by side. Deep Blue is more muted, cooler than Naggaroth Night.

Can I use Deep Blue instead of Naggaroth Night?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Deep Blue is more muted, cooler than Naggaroth Night.

Can I use Naggaroth Night instead of Deep Blue?

The same difference applies the other way round: Naggaroth Night is more saturated, warmer.

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.