Violet Coven vs Faded Ultramarine

How close are they?

ΔE 17.0, loose: different enough that you should pick on purpose. Faded Ultramarine is a little darker, more saturated, cooler than Violet Coven.

Can I use Faded Ultramarine instead of Violet Coven?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Faded Ultramarine is a little darker, more saturated, cooler than Violet Coven.

Can I use Violet Coven instead of Faded Ultramarine?

The same difference applies the other way round: Violet Coven is a little lighter, 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.