ΔE 18.0, loose: different enough that you should pick on purpose. Blue is a little lighter, much more saturated, warmer than Blue Black.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Blue is a little lighter, much more saturated, warmer than Blue Black.
The same difference applies the other way round: Blue Black is a little darker, much 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.
See Blue Black on the colour wheel See Blue on the colour wheel
All matches: Blue Black equivalents · Blue equivalents