Augur Blue vs Runic Purple

How close are they?

ΔE 22.1, loose: different enough that you should pick on purpose. Runic Purple is noticeably darker, more saturated, warmer than Augur Blue.

Can I use Runic Purple instead of Augur Blue?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Runic Purple is noticeably darker, more saturated, warmer than Augur Blue.

Can I use Augur Blue instead of Runic Purple?

The same difference applies the other way round: Augur Blue is noticeably lighter, more muted, 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.