ΔE 11.6, fair: the same colour family, but not a straight swap. Celestial Violet is a little darker, more muted, warmer than Let Them Eat Cake.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Celestial Violet is a little darker, more muted, warmer than Let Them Eat Cake.
The same difference applies the other way round: Let Them Eat Cake is a little lighter, 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 Let Them Eat Cake on the colour wheel See Celestial Violet on the colour wheel
All matches: Let Them Eat Cake equivalents · Celestial Violet equivalents