ΔE 10.7, fair: the same colour family, but not a straight swap. Blue Gray is a little darker, warmer than Temple Guard Blue.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Blue Gray is a little darker, warmer than Temple Guard Blue.
The same difference applies the other way round: Temple Guard Blue is a little lighter, 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 Temple Guard Blue on the colour wheel See Blue Gray on the colour wheel
All matches: Temple Guard Blue equivalents · Blue Gray equivalents