Reports from big retailers for 2012’s holiday season were generally positive:1. Birks & Mayors’ same-store sales during the holiday season increased 5 percent, led by a 6 percent comp gain in the United States. Canadian comps rose 4 percent.2. Zale Corp. announced that comp sales increased 2.3 percent for its holiday period, which it defines as November and December.3. Tiffany & Co.’s worldwide comp sales were flat for the holiday months of November and December, although net sales increased 4 percent.4. Signet’s same-store U.S. holiday sales rose 4.7 percent. Holiday comp sales at its Kay Jewelers division rose 5.8 percent, while comps at Jared the Galleria of Jewelry rose 4.8 percent.5. Samuels Jewelers said comp store sales for the nine-week holiday season jumped 8.4 percent, with December comps rising 11.2 percent.