ΔE 11.8, fair: the same colour family, but not a straight swap. Obsidian Black is a little lighter, more muted than Green Pearl.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Obsidian Black is a little lighter, more muted than Green Pearl.
The same difference applies the other way round: Green Pearl is a little darker, 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 Green Pearl on the colour wheel See Obsidian Black on the colour wheel
All matches: Green Pearl equivalents · Obsidian Black equivalents