Fine jewelry (e.g. gold, silver and precious stones) in Brazil is more expensive than you'll find…read morein the US. Ouro Design is one of the more reasonable shops if you're looking to buy while here. Their store is rather beautiful and looks almost opulent for a shop in a Mall.
They sell mostly gold jewelry, but also have some nice silver pieces as well. In addition to jewelry, they also sell watches, but the only brand I was familiar with was Bulova and they cost about 5 times more here, so I wouldn't recommend them as a place to get a new timepiece.
The staff are very friendly and professional. While you're shopping, they may offer you a licqueur to help you get over the prices.