Highlord Blue vs Fairy Blood

How close are they?

ΔE 17.7, loose: different enough that you should pick on purpose. Fairy Blood is a little darker, much more muted, warmer than Highlord Blue.

Can I use Fairy Blood instead of Highlord Blue?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Fairy Blood is a little darker, much more muted, warmer than Highlord Blue.

Can I use Highlord Blue instead of Fairy Blood?

The same difference applies the other way round: Highlord Blue is a little lighter, much 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.