At place vendome A few hours before we met the last time. And I also liked it a lot before I had it in. It’s really thick and heavy. In the end I found the setting the watch to be over complicated. So much that the lady didn’t even know how to explain ( which is not a fault of the watch in the end).
The dark is silver reaction with your skin/transpiration. Most probably silversulfide. Gold is inert. So either you polish it with silver cloth, leave it as it is or have gold layer replaced. You could even try putting a gold leaf to try it yourself.