ΔE 5.2, very close: most people won’t see a difference side by side. Onyx Skin is a little darker than Matt Ash Black. They are different kinds of paint: AMMO by Mig Matt Ash Black is an ink, glaze or transparent paint and Army Painter Onyx Skin is an opaque base/layer paint, so they won’t behave the same on the model even where the colour is close.
Yes, for most jobs. Very close match (ΔE 5). Onyx Skin is a little darker than Matt Ash Black. They are different kinds of paint.
The same difference applies the other way round: Matt Ash Black is a little lighter.
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 Onyx Skin on the colour wheel
All matches: Matt Ash Black equivalents · Onyx Skin equivalents