ΔE 9.2, close: similar, with a visible difference side by side. Nocturne Green is a little lighter, more saturated, cooler than Obsidian Pigment Toner.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Nocturne Green is a little lighter, more saturated, cooler than Obsidian Pigment Toner.
The same difference applies the other way round: Obsidian Pigment Toner is a little darker, more muted, warmer.
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 Obsidian Pigment Toner on the colour wheel See Nocturne Green on the colour wheel
All matches: Obsidian Pigment Toner equivalents · Nocturne Green equivalents