Phantom Blue vs Autumn Sage

How close are they?

ΔE 8.1, close: similar, with a visible difference side by side. Autumn Sage is a little darker, warmer than Phantom Blue.

Can I use Autumn Sage instead of Phantom Blue?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Autumn Sage is a little darker, warmer than Phantom Blue.

Can I use Phantom Blue instead of Autumn Sage?

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