ΔE 11.8, fair: the same colour family, but not a straight swap. Thallax Gold is a little darker, more saturated than Brass.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Thallax Gold is a little darker, more saturated than Brass.
The same difference applies the other way round: Brass is a little lighter, 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.
See Brass on the colour wheel See Thallax Gold on the colour wheel
All matches: Brass equivalents · Thallax Gold equivalents