Luxion Purple vs Blue

How close are they?

ΔE 22.9, loose: different enough that you should pick on purpose. Blue is a little lighter, more saturated, cooler than Luxion Purple.

Can I use Blue instead of Luxion Purple?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 23). Blue is a little lighter, more saturated, cooler than Luxion Purple.

Can I use Luxion Purple instead of Blue?

The same difference applies the other way round: Luxion Purple 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.