Dark Sky vs Cerulean Blue Deep

How close are they?

ΔE 11.5, fair: the same colour family, but not a straight swap. Cerulean Blue Deep is a little lighter, more saturated than Dark Sky.

Can I use Cerulean Blue Deep instead of Dark Sky?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Cerulean Blue Deep is a little lighter, more saturated than Dark Sky.

Can I use Dark Sky instead of Cerulean Blue Deep?

The same difference applies the other way round: Dark Sky is a little darker, more muted.

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.