Plate Mail Metal vs Peridot Alchemy

How close are they?

ΔE 19.6, loose: different enough that you should pick on purpose. Peridot Alchemy is a little darker, much more saturated than Plate Mail Metal.

Can I use Peridot Alchemy instead of Plate Mail Metal?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Peridot Alchemy is a little darker, much more saturated than Plate Mail Metal.

Can I use Plate Mail Metal instead of Peridot Alchemy?

The same difference applies the other way round: Plate Mail Metal is a little lighter, much 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.