Unfortunately for oldies like me, I remember the true implications of the steel and copper shortages of the 60's and 70's in which in the UK e.g. specific steel grades were rationed to industry on a strict prioritisation basis and copper couldn't be had for love or money. Occassionally you still come across old steel electrical wiring from this time.
So if quinnessential industries couldn't get essential supplies, I doubt copper for jewelry manufacturer was top of the list.
Its just something else to bear in mind when questioning why such things happened and why variations exist................its not always what you first think.