The shares rose $1.73 to $5.76 at 4:02 p.m. in New York Stock Exchange composite trading, the most since April 2009.

Zale said yesterday that sales at stores open at least a year rose 8.5 percent over the combined November-December 2010 period as shoppers bought more diamonds. Same-store holiday sales in 2009 fell 12 percent.

The gain was announced a year after the company replaced its chief executive officer and the heads of stores and merchandising. The company lost more than $280 million in the past two years. Two analysts surveyed by Retail Metrics Inc. estimated a 3 percent sales gain in the current quarter, which began on Nov. 1.

Zale is refocusing its merchandise on diamonds and stepping up training of its workers, Chief Executive Officer Theo Killion said in an interview yesterday. The company increased the number of salespeople certified by the Diamond Council of America to 2,000, from 800 last year, and plans to add more, he said.

Killion won the job in September after serving on an interim basis since January 2010.

Zale, based in Irving, Texas, is exploring the sale of its Piercing Pagoda business, with Apollo Global Management LLC among firms looking at the division, people familiar with the matter said last month. Zale executives declined to comment on the status of the unit.