Gravelord Grey vs Dark Green Blue

How close are they?

ΔE 18.0, loose: different enough that you should pick on purpose. Dark Green Blue is noticeably darker, more saturated than Gravelord Grey.

Can I use Dark Green Blue instead of Gravelord Grey?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Dark Green Blue is noticeably darker, more saturated than Gravelord Grey.

Can I use Gravelord Grey instead of Dark Green Blue?

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

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.