I haven't taken my wedding ring off for years but did today ( idle twiddling) and it is revolting. I presume that's decades of soap scum and dead skin cells.
Found this if it helps.
Line small dish with foil. Add layer of salt, layer of bicarb of soda and some fairy liquid. Add hot water and soak ring for ten minutes. Scrub with old toothbrush. Dry and buff to new.