ΔE 11.3, fair: the same colour family, but not a straight swap. Celestial Blue is a little lighter, more saturated than Russ Grey.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Celestial Blue is a little lighter, more saturated than Russ Grey.
The same difference applies the other way round: Russ Grey is a little darker, 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.
See Russ Grey on the colour wheel See Celestial Blue on the colour wheel
All matches: Russ Grey equivalents · Celestial Blue equivalents