Highlord Blue vs Cerulean Blue Deep

How close are they?

ΔE 12.8, fair: the same colour family, but not a straight swap. Cerulean Blue Deep is noticeably darker, more muted than Highlord Blue. They are different kinds of paint: Army Painter Highlord Blue is a one-coat contrast-style paint and Golden Cerulean Blue Deep is an opaque base/layer paint, so they won’t behave the same on the model even where the colour is close.

Can I use Cerulean Blue Deep instead of Highlord Blue?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Cerulean Blue Deep is noticeably darker, more muted than Highlord Blue. They are different kinds of paint.

Can I use Highlord Blue instead of Cerulean Blue Deep?

The same difference applies the other way round: Highlord Blue is noticeably 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.