Augur Blue vs Decadent Purple

How close are they?

ΔE 6.8, close: similar, with a visible difference side by side. Decadent Purple is more muted, warmer than Augur Blue.

Can I use Decadent Purple instead of Augur Blue?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Decadent Purple is more muted, warmer than Augur Blue.

Can I use Augur Blue instead of Decadent Purple?

The same difference applies the other way round: Augur 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.