ΔE 6.2, close: similar, with a visible difference side by side. Ultimate Cup of Coffee is a little lighter than Obsidian Skin.
Usually, if you are not matching paint already on the model. Close match (ΔE 6). Ultimate Cup of Coffee is a little lighter than Obsidian Skin.
The same difference applies the other way round: Obsidian Skin is a little darker.
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 Skin on the colour wheel See Ultimate Cup of Coffee on the colour wheel
All matches: Obsidian Skin equivalents · Ultimate Cup of Coffee equivalents