ΔE 10.6, fair: the same colour family, but not a straight swap. Iridescent Copper Light (Fine) is a little darker, more muted than Fulgurite Copper. They are different kinds of paint: Citadel Fulgurite Copper is a metallic and Golden Iridescent Copper Light (Fine) is a pearl paint, so they won’t behave the same on the model even where the colour is close.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Iridescent Copper Light (Fine) is a little darker, more muted than Fulgurite Copper. They are different kinds of paint.
The same difference applies the other way round: Fulgurite Copper is a little lighter, 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 Fulgurite Copper on the colour wheel See Iridescent Copper Light (Fine) on the colour wheel
All matches: Fulgurite Copper equivalents · Iridescent Copper Light (Fine) equivalents