** Chow Tai Fook Jewellery Group 1929.HK slips 4.6% to HK$9.19; biggest pct loser on Hang Seng Index .HSI

** HK-based jeweller's retail sales value falls 11.6% y/y in three months ended March 31

** Same-store sales slips 13.2% y/y in mainland China, 22.5% in Hong Kong and Macau in reported period

** Rivals Laopu Gold 6181.HK down 3.8%, Luk Fook 0590.HK dips 1.7%; Lao Feng Xiang 600612.SS adds 0.4%

** YTD, Chow Tai Fook stock gains 37.7%

(Reporting by Donny Kwok)

((donny.kwok@thomsonreuters.com))