ΔE 14.5, fair: the same colour family, but not a straight swap. Emerald is noticeably darker, warmer than Blue-Green.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). Emerald is noticeably darker, warmer than Blue-Green.
The same difference applies the other way round: Blue-Green is noticeably 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 Blue-Green on the colour wheel See Emerald on the colour wheel
All matches: Blue-Green equivalents · Emerald equivalents