Gold laid over a dark finish has a problem that gold on ivory does not: the dark comes through it.
A deep polish is a coloured finish, and until it is fully sealed it will continue to give up a little of that colour to anything laid on top. Put gold straight onto it and within weeks the bright metal has gone muddy and slightly brown from beneath - not evenly, which would at least look deliberate, but in patches wherever the underlying finish was thickest.
So the sequence matters. The dark polish goes on first over the whole piece, carving included, and is left to cure properly rather than to the touch. A sealing coat then goes over the areas that will be gilded, isolating the colour beneath. Only after that is the gold applied.
It means the gilding happens late, and it means a dark-and-gold set takes longer than a pale-and-gold one - the dark ground has to be genuinely finished before the bright work starts.
The alternative is to gild first and polish around it, which is faster and leaves a dark edge crawling into every gold line. We have seen furniture made that way. It looks acceptable in the showroom and wrong within a year.