Asurmen Blue vs Legacy Blue

How close are they?

ΔE 25.0, loose: different enough that you should pick on purpose. Legacy Blue is noticeably darker, more muted, warmer than Asurmen Blue.

Can I use Legacy Blue instead of Asurmen Blue?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 25). Legacy Blue is noticeably darker, more muted, warmer than Asurmen Blue.

Can I use Asurmen Blue instead of Legacy Blue?

The same difference applies the other way round: Asurmen Blue is noticeably lighter, 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.