Cobalt Blue vs Gunmetal Blue

How close are they?

ΔE 9.4, close: similar, with a visible difference side by side. Gunmetal Blue is more muted, warmer than Cobalt Blue.

Can I use Gunmetal Blue instead of Cobalt Blue?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Gunmetal Blue is more muted, warmer than Cobalt Blue.

Can I use Cobalt Blue instead of Gunmetal Blue?

The same difference applies the other way round: Cobalt Blue is more saturated, 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.