ΔE 12.8, fair: the same colour family, but not a straight swap. Black Green is a little darker, more muted than Emerald Green.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Black Green is a little darker, more muted than Emerald Green.
The same difference applies the other way round: Emerald Green is a little lighter, more saturated.
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 Emerald Green on the colour wheel See Black Green on the colour wheel
All matches: Emerald Green equivalents · Black Green equivalents