ΔE 18.1, loose: different enough that you should pick on purpose. Dark Grey Blue is much more muted, cooler than Gothic Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Dark Grey Blue is much more muted, cooler than Gothic Blue.
The same difference applies the other way round: Gothic Blue is much 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.
See Gothic Blue on the colour wheel See Dark Grey Blue on the colour wheel
All matches: Gothic Blue equivalents · Dark Grey Blue equivalents