Deep Azure vs Dark Jade

How close are they?

ΔE 15.8, loose: different enough that you should pick on purpose. Dark Jade is noticeably darker, more muted, warmer than Deep Azure.

Can I use Dark Jade instead of Deep Azure?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Dark Jade is noticeably darker, more muted, warmer than Deep Azure.

Can I use Deep Azure instead of Dark Jade?

The same difference applies the other way round: Deep Azure is noticeably lighter, more saturated, cooler.

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.