Golden Armour vs Fire Opal

How close are they?

ΔE 19.0, loose: different enough that you should pick on purpose. Fire Opal is a little lighter, much more muted than Golden Armour.

Can I use Fire Opal instead of Golden Armour?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Fire Opal is a little lighter, much more muted than Golden Armour.

Can I use Golden Armour instead of Fire Opal?

The same difference applies the other way round: Golden Armour is a little 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.