Periwinkle Purple vs Cygnar Blue Highlight

How close are they?

ΔE 17.5, loose: different enough that you should pick on purpose. Cygnar Blue Highlight is a little lighter, cooler than Periwinkle Purple. They are different kinds of paint: Army Painter Periwinkle Purple is a one-coat contrast-style paint and Formula P3 Cygnar Blue Highlight 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 Cygnar Blue Highlight instead of Periwinkle Purple?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Cygnar Blue Highlight is a little lighter, cooler than Periwinkle Purple. They are different kinds of paint.

Can I use Periwinkle Purple instead of Cygnar Blue Highlight?

The same difference applies the other way round: Periwinkle Purple is a little darker, 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.