ΔE 7.3, close: similar, with a visible difference side by side. Cement Grey is more muted, warmer than IJA Gray.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Cement Grey is more muted, warmer than IJA Gray.
The same difference applies the other way round: IJA Gray is 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 IJA Gray on the colour wheel See Cement Grey on the colour wheel
All matches: IJA Gray equivalents · Cement Grey equivalents