...NEW YORK (S&P Global Ratings) Dec. 7, 2018--S&P Global Ratings today said that while diamond and specialty jewelry retailer Signet Jewelers Ltd. (##+/Negative/--) reported decent third-quarter sales growth, the company indicated that competition has intensified for the holiday shopping season. This leads us to believe that Signet's credit metrics could worsen somewhat, reducing its cushion for an operational underperformance and further weakening prospects for the company. Signet attributes the intensified competitive environment to department stores' heightened focus on the jewelry category and a shift in consumer preferences toward value-priced merchandise. During the third quarter, Signet reported comparable sales growth of 1.6% and gross margin expansion of about 350 basis points. The company's performance during the quarter benefited from good sales momentum at Zales and Piercing Pagoda as well as the completion of its credit outsourcing prior to the third quarter, which no longer...