Blue vs Deep Sky Blue

How close are they?

ΔE 15.5, loose: different enough that you should pick on purpose. Deep Sky Blue is a little lighter, much more muted, cooler than Blue.

✓ AMMO ATOM user guide chart lists these two as equivalents.

Can I use Deep Sky Blue instead of Blue?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Deep Sky Blue is a little lighter, much more muted, cooler than Blue.

Can I use Blue instead of Deep Sky Blue?

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