Star Blue vs Incubi Darkness

How close are they?

ΔE 7.9, close: similar, with a visible difference side by side. Incubi Darkness is a little darker, more muted than Star Blue.

Can I use Incubi Darkness instead of Star Blue?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Incubi Darkness is a little darker, more muted than Star Blue.

Can I use Star Blue instead of Incubi Darkness?

The same difference applies the other way round: Star Blue is a little lighter, more saturated.

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.