Emerald Alchemy vs Dusken Green

How close are they?

ΔE 22.2, loose: different enough that you should pick on purpose. Dusken Green is noticeably darker, more saturated, warmer than Emerald Alchemy.

Can I use Dusken Green instead of Emerald Alchemy?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Dusken Green is noticeably darker, more saturated, warmer than Emerald Alchemy.

Can I use Emerald Alchemy instead of Dusken Green?

The same difference applies the other way round: Emerald Alchemy is noticeably lighter, more muted, 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.