WOPL Sniffer
Veteran and General Yakker
I've never done it, but I think a battery charger and an electrolyte solution bath would do it.
You could first reverse plate the existing gold off, polish/refine the case underneath, and then re-plate it.
I'm not sure what base metal they used at Omega for plating back then... Modern gold Omega watches are solid, like Rolex always has been.
Jim, what's it take to disassemble this Omega? I found this place that does nothing but replating watch cases but you have to disassemble the watch and send them nothing but the case and the back. The back is off but I never took one apart before.