Tiffany's ( TIF) first-quarter earnings shimmered, jumping 10% on strong sales. The results beat analysts' estimates by a penny, and the company affirmed its expected full-year earnings, which match the analyst consensus. The shares added about 10% to $30.50 on the Instinet premarket. In the three months ended April 30, the New York-based jeweler earned $35.9 million, compared with $32.7 million in the prior-year period. Earnings per share were 24 cents, compared with 22 cents last year. Analysts expected 23 cents a share. Sales grew 14% to $396 million. The company cited growth in its U.S. and international markets. On a constant exchange rate basis, Tiffany's said sales grew 10% with a 0.4% comparable worldwide sales increase. U.S. comparable-store sales rose 2% during the quarter. The company said it's on track to meet its aforementioned 2003 guidance. Tiffany's said it expects a low-teens percentage increase in annual net sales and a mid-to-high single-digit increase in net earnings, in the range of $1.33 to $1.38 a share. Analysts expect $1.34 a share, on average. The company earned $1.23 a share last year.