ΔE 14.6, fair: the same colour family, but not a straight swap. French Blue is a little lighter, more saturated, cooler than Violet.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). French Blue is a little lighter, more saturated, cooler than Violet.
The same difference applies the other way round: Violet is a little darker, more muted, warmer.
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 Violet on the colour wheel See French Blue on the colour wheel
All matches: Violet equivalents · French Blue equivalents