ΔE 17.7, loose: different enough that you should pick on purpose. Silver Grey is a little darker, warmer than Ion Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Silver Grey is a little darker, warmer than Ion Blue.
The same difference applies the other way round: Ion 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 Ion Blue on the colour wheel See Silver Grey on the colour wheel
All matches: Ion Blue equivalents · Silver Grey equivalents