Updated from 10:49 a.m. ESTSAN FRANCISCO -- The slowdown in U.S. consumer spending has now tarnished Tiffany ( TIF). Shares of the jewelry purveyor tumbled 12% Friday after the company reported soft holiday sales in the U.S. and trimmed its earnings projection. While difficult comparisons from a year ago were partly to blame, Tiffany said the weakness was worse than expected, fueling concerns that recent consumer troubles aren't limited to lower-income shoppers. Tiffany's same-store sales, or sales at stores open at least a year, fell 2% in the U.S. for the two-month period ended Dec. 31, as traffic trends weakened. Worldwide, same-store sales were up 3%. "We entered the holiday season facing well-known, challenging macro conditions in the U.S. and these results reflect it," said Mark Aaron, vice president of investor relations, in a conference call. "Therefore, soft U.S. results were not too surprising, although the magnitude of the softness in our stores and direct marketing sales was more than we expected." Tiffany's total U.S. sales edged up 4% in the holiday period, while international sales jumped 18%. The company did record a 10% increase in sales at its New York flagship store during the holiday period, as foreign tourists took advantage of the weak dollar. The flagship 5th Avenue store played a big role in propping up results. For instance, Aaron said on the call that seven of Tiffany's stores just outside of New York City had a combined 10% drop in same-store sales for the period.