HONG KONG, China — One of the worst analyst-rated jewellery retailers in Hong Kong has caught the attention of the world's largest asset manager.BlackRock Inc. increased its stake in Chow Tai Fook Jewellery Group Ltd., and added the stock to its global long/short equity fund in the third quarter, according to data compiled by Bloomberg. European investment firms Gamax Management AG and Robeco Groep NV made their initial purchases earlier in the year.It’s been a tough year for the world’s biggest publicly traded jewellery chain. Chow Tai Fook’s same-store sales in Hong Kong and Macau fell 20 percent in the three months ended June from a year earlier, hurt by fewer mainland visitors. Hong Kong’s retail sales have fallen every month since March 2015 amid a slowing Chinese economy and President Xi Jinping’s anti-corruption and austerity drives, with jewellery, watches and other luxury goods the hardest hit.Managing director Kent Wong in July predicted revenue to decline even further, without providing specific figures.Only two analysts have a buy recommendation on Chow Tai Fook, compared with 21 at the end of 2014. The company scores 2.21 out of 5 for consensus analyst ratings, one of the lowest in the industry, according to data compiled by Bloomberg.Even so, a recovery may be in sight. Chow Tai Fook shares have risen 10 percent this year, on track for its first annual gain since listing in December 2011. The stock slumped 52 percent last year.“The worst may be over for Chow Tai Fook in terms of Hong Kong and Macau retail sales,” Catherine Lim, a Singapore-based analyst at Bloomberg Intelligence, said by phone. “The company has been cutting costs, and as long as sales don’t deteriorate, they may actually be able to exceed profit estimates.”In July, Chow Tai Fook’s chairman Cheng Kar Shun sold his entire holdings in the company, which he’s held since 2012, according to regulatory filings. A spokesperson for Chow Tai Fook declined to comment on the chairman’s decision to sell his stock.BlackRock declined to comment on its investment in Chow Tai Fook. It held 1.04 million shares as of Aug. 31, according to Bloomberg data.By Lisa Pham, with assistance from Daniela Wei ; editors: Divya Balji and Teo Chian Wei.