Right now messing with a couple ∅17mm SST40 biscotti clone drivers, for temperature protection removal and spring conductance enhacement, and I see these feature some sort of improved, wide top spring with flattened spiral ending:

They look to be gold :???: plated. What metal alloy are these made of? Some phosphor bronze? What IACS conductivity?

I am wondering if I should care to replace them. The driver spring backside pad diameter has a weird size, neither small nor big springs from BlueSwordM fit very right.