Chancellor Blue vs Dark Grey

How close are they?

ΔE 9.5, close: similar, with a visible difference side by side. Dark Grey is a little darker, more muted than Chancellor Blue.

Can I use Dark Grey instead of Chancellor Blue?

Usually, if you are not matching paint already on the model. Close match (ΔE 10). Dark Grey is a little darker, more muted than Chancellor Blue.

Can I use Chancellor Blue instead of Dark Grey?

The same difference applies the other way round: Chancellor Blue is a little lighter, more saturated.

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.