ΔE 10.8, fair: the same colour family, but not a straight swap. IJA Gray is a little darker, more muted, warmer than Autumn Sage.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). IJA Gray is a little darker, more muted, warmer than Autumn Sage.
The same difference applies the other way round: Autumn Sage 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.
See Autumn Sage on the colour wheel See IJA Gray on the colour wheel
All matches: Autumn Sage equivalents · IJA Gray equivalents