Phantasmal Blue vs Cursed Blue

How close are they?

ΔE 16.3, loose: different enough that you should pick on purpose. Cursed Blue is a little darker, more muted, cooler than Phantasmal Blue.

Can I use Cursed Blue instead of Phantasmal Blue?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Cursed Blue is a little darker, more muted, cooler than Phantasmal Blue.

Can I use Phantasmal Blue instead of Cursed Blue?

The same difference applies the other way round: Phantasmal Blue is a little lighter, more saturated, 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.