Ducat Blue vs Aegis Aqua

How close are they?

ΔE 11.8, fair: the same colour family, but not a straight swap. Aegis Aqua is a little darker, more muted than Ducat Blue.

Can I use Aegis Aqua instead of Ducat Blue?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Aegis Aqua is a little darker, more muted than Ducat Blue.

Can I use Ducat Blue instead of Aegis Aqua?

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

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.