Sky Blue vs Russ Grey

How close are they?

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

Can I use Russ Grey instead of Sky Blue?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Russ Grey is a little darker, more muted, warmer than Sky Blue.

Can I use Sky Blue instead of Russ Grey?

The same difference applies the other way round: Sky Blue is a little 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.