A fascinating watch: Solid Gold C-Cased Japanese? Genéve in a Seamaster case

I'm truly fascinated by this watch, it's so unbelievably unique, I don't know whether it's original, but even if it's not, every part is fascinating on it's own, there's the Genéve dial with the Swiss Made above the indices which as far as I know is from a Japanese model, there's the C-Case, but with a Seamaster caseback? - and that unique bracelet which I've never seen before - there's a spacer near the 565 movement, so it's not a Constellation case either - yet the bracelet is reported as 19mm, which defies my sense of dimension

https://www.catawiki.com/en/l/52525353-omega-seamaster-31463332-men-1960-1969