ΔE 38.4, loose: different enough that you should pick on purpose. Iridescent Stainless Steel (Coarse) is noticeably lighter, much more muted than Dark Emerald. They are different kinds of paint: Army Painter Dark Emerald is a metallic and Golden Iridescent Stainless Steel (Coarse) is a pearl paint, so they won’t behave the same on the model even where the colour is close.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 38). Iridescent Stainless Steel (Coarse) is noticeably lighter, much more muted than Dark Emerald. They are different kinds of paint.
The same difference applies the other way round: Dark Emerald is noticeably darker, much 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.
See Dark Emerald on the colour wheel See Iridescent Stainless Steel (Coarse) on the colour wheel
All matches: Dark Emerald equivalents · Iridescent Stainless Steel (Coarse) equivalents