ΔE 10.5, fair: the same colour family, but not a straight swap. Steel Grey is a little darker, cooler than Sapphire Blue.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Steel Grey is a little darker, cooler than Sapphire Blue.
The same difference applies the other way round: Sapphire Blue is a little lighter, warmer.
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 Sapphire Blue on the colour wheel See Steel Grey on the colour wheel
All matches: Sapphire Blue equivalents · Steel Grey equivalents