To admirers she was a force field, one of the few women to rise to leadership positions in retailing, wielding clout, first as Bergdorf’s vice president and fashion director, then as president. She was also among the first to snap up and promote designers including Ms. Karan, Giorgio Armani, Azzedine Alaïa, Kate Spade and Tom Ford at the start of their careers.

“To me that was it, to be the first kid on the block with a new talent or new idea,” Ms. Mello said in 2009.

Colleagues and friends ascribed her success to a combination of intuitiveness and judicious timing.

“To succeed in this field, you had to have pretty good instincts from a merchandising standpoint,” said Joe Cicio, a longtime friend and a former top executive at Macy’s and I. Magnin. “She was current. She had an uncanny eye. If she asked you to take a look at something, a new designer’s sketches or portfolio, that’s what you did.”

Robert Burke, who succeeded Ms. Mello at Bergdorf and is now a luxury retail consultant, summed up her influence: “She took a position.”

In the ’80s and early ’90s, “an effective fashion director had the idea, sourced it, manufactured it, figured out how to promote it, how to extend its life,” Mr. Burke said. “Then she or he figured out what to do with it, in case it didn’t work.”