ΔE 12.4, fair: the same colour family, but not a straight swap. Violet Vamp is more muted, warmer than Imperium Blue.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Violet Vamp is more muted, warmer than Imperium Blue.
The same difference applies the other way round: Imperium Blue is more saturated, 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 Imperium Blue on the colour wheel See Violet Vamp on the colour wheel
All matches: Imperium Blue equivalents · Violet Vamp equivalents