ΔE 14.8, fair: the same colour family, but not a straight swap. Middle Stone is a little darker, warmer than Nurgling Green.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). Middle Stone is a little darker, warmer than Nurgling Green.
The same difference applies the other way round: Nurgling Green 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 Nurgling Green on the colour wheel See Middle Stone on the colour wheel
All matches: Nurgling Green equivalents · Middle Stone equivalents