Grey-Blue 1920s-1930s vs Autumn Sage

How close are they?

ΔE 13.2, fair: the same colour family, but not a straight swap. Autumn Sage is a little darker, much more saturated than Grey-Blue 1920s-1930s.

Can I use Autumn Sage instead of Grey-Blue 1920s-1930s?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Autumn Sage is a little darker, much more saturated than Grey-Blue 1920s-1930s.

Can I use Grey-Blue 1920s-1930s instead of Autumn Sage?

The same difference applies the other way round: Grey-Blue 1920s-1930s is a little lighter, much 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.