Given the downturn in China and general economic woes worldwide, the mood was surprisingly upbeat at the Hong Kong Jewellery & Gem Fair, with many exhibitors confessing that, while they hadn’t expected much, a stronger presence of American buyers was cause for optimism among traders.A total of 3,526 companies from 48 countries, including 204 from the United States, exhibited at the fair, held at the AsiaWorld-Expo Sept. 19–23 and Hong Kong Convention and Exhibition Centre Sept. 21–25. Organizer UBM Asia Ltd. reported slightly more than 51,000 visitors, with Hong Kong, China, India, and the United States sending the largest delegations.Pietro Minghi, director of Miiori New York, which displayed a range of jewelry from the Robert Procop–designed Style of Jolie line, said he was buoyed by the response to the brand’s emerald pieces at the fair and at a preshow private event.&nb