ΔE 10.7, fair: the same colour family, but not a straight swap. Ink Violet is warmer than Gothic Blue. They are different kinds of paint: Army Painter Gothic Blue is an opaque base/layer paint and Vallejo Ink Violet is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Ink Violet is warmer than Gothic Blue. They are different kinds of paint.
The same difference applies the other way round: Gothic Blue is cooler.
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 Gothic Blue on the colour wheel See Ink Violet on the colour wheel
All matches: Gothic Blue equivalents · Ink Violet equivalents