ΔE 24.2, loose: different enough that you should pick on purpose. Ink Skin is noticeably darker, much more saturated than Matt Ash Black.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 24). Ink Skin is noticeably darker, much more saturated than Matt Ash Black.
The same difference applies the other way round: Matt Ash Black is noticeably lighter, much more muted.
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 Matt Ash Black on the colour wheel See Ink Skin on the colour wheel
All matches: Matt Ash Black equivalents · Ink Skin equivalents