Beowulf Blue vs Celestium Blue

How close are they?

ΔE 17.5, loose: different enough that you should pick on purpose. Celestium Blue is noticeably lighter, more muted, cooler than Beowulf Blue.

Can I use Celestium Blue instead of Beowulf Blue?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Celestium Blue is noticeably lighter, more muted, cooler than Beowulf Blue.

Can I use Beowulf Blue instead of Celestium Blue?

The same difference applies the other way round: Beowulf Blue is noticeably darker, more saturated, warmer.

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.