Stone Grey vs Terminatus Stone

How close are they?

ΔE 7.4, close: similar, with a visible difference side by side. Terminatus Stone is a little lighter, more saturated, cooler than Stone Grey.

Can I use Terminatus Stone instead of Stone Grey?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Terminatus Stone is a little lighter, more saturated, cooler than Stone Grey.

Can I use Stone Grey instead of Terminatus Stone?

The same difference applies the other way round: Stone Grey is a little darker, more muted, 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.