ΔE 6.3, close: similar, with a visible difference side by side. Iridescent Stainless Steel (Fine) is a little lighter than Necron Compound. They are different kinds of paint: Citadel Necron Compound is a metallic and Golden Iridescent Stainless Steel (Fine) is a pearl paint, so they won’t behave the same on the model even where the colour is close.
Usually, if you are not matching paint already on the model. Close match (ΔE 6). Iridescent Stainless Steel (Fine) is a little lighter than Necron Compound. They are different kinds of paint.
The same difference applies the other way round: Necron Compound is a little darker.
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 Necron Compound on the colour wheel See Iridescent Stainless Steel (Fine) on the colour wheel
All matches: Necron Compound equivalents · Iridescent Stainless Steel (Fine) equivalents