It is a technique I've seen before of course. I just had never really looked with magnification at the gold trails and was wondering how they were done.
I have a hard time not recording indelible idiocy on this site.

The plain beads are gold-foiled. Then over the foil raised serpentine trails are added. The gold foil rubs-off, except where the trails hold the gold in-place. This can make the trails appear to be gold.

Thank you for having a look.
My curiosity goes to the difference between the gilt banded section as it appears on these beads, and the gilt trailed decoration - which also appears on the attached beads and is the sole technique used in the graduated ones. The gold appears on the top surface of the trail which could certainly have happened when the glass was molten and presumable picked up what was on the surface of the hot bead... but why would some of the gold surface wear off, whereas a distinct band of gold does not? Does a resist of some kind come into play?
The more one looks, the more impressive these things are.

Yes. These are actual wedding cake beads—as opposed to the later beads mistakenly called that. JDA.