Antonio's in PP would have my vote, too.
Patrick is also great, especially if you want silver, not gold (as the name implies). White gold, especially, doesn't seem to be too easy to come by here.
With regards to the place next to Bon, be prepared to keep going back to find someone there, unless they have had a change of staff. I wouldn't part with any money or jewelery in advance. I took a watch there for a new battery and he promised he'd get me one. I left the watch as it was worth next to nothing but gave up in the end as the place was never open.