Tiffany (TIF) shares fell sharply after the upscale jeweler reported that comparable store sales over the critical two-month holiday selling season were flat in all geographies with the lone exception of China. The upscale jeweler also cut its full-year earnings forecast, saying it now expects to come in at the low end of its own prior outlook of $3.20 to $3.40 earnings per share. Analysts were looking for $3.26 a share. Tiffany shares were down