Coven Purple vs Smalt Hue

How close are they?

ΔE 18.4, loose: different enough that you should pick on purpose. Smalt Hue is noticeably lighter, cooler than Coven Purple.

Can I use Smalt Hue instead of Coven Purple?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Smalt Hue is noticeably lighter, cooler than Coven Purple.

Can I use Coven Purple instead of Smalt Hue?

The same difference applies the other way round: Coven Purple is noticeably darker, 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.