ΔE 9.9, close: similar, with a visible difference side by side. Middle Stone is a little lighter, warmer than Field Green FS 34097.
Usually, if you are not matching paint already on the model. Close match (ΔE 10). Middle Stone is a little lighter, warmer than Field Green FS 34097.
The same difference applies the other way round: Field Green FS 34097 is a little darker, 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 Field Green FS 34097 on the colour wheel See Middle Stone on the colour wheel
All matches: Field Green FS 34097 equivalents · Middle Stone equivalents