The wire used for stringing pearls / beads etc is gold-plated bronze i.e. NOT gold for all - jadau as well as thappa.
The reasons why, by default, we string in gold-plated bronze wire are :
1. the look is no different when done in gold wire
2. stringing it in a bronze wire gives us the flexibility to change the stringing (and hence the look) anytime in future without having to worry about the gold wastage that occurs when we cut apart a stringing that's done in gold wire
Having said that, if you wish.. we can certainly have any piece’s stringing changed to gold wire. Additional cost against the same will be notified and added.