Today’s best CEOs know that a dose of social responsibility helps attract and keep customers and employees.

Most companies give around 1% of their pre-tax profits to philanthropic causes. One that stands above the crowd: Target . The big-box retailer gives more than 5% of its pre-tax income to support communities. The 5% pledge, which Target proudly promotes, translates to more than $3 million in giving each week.

Last evening in Manhattan, another retail chief who sells at the opposite end of “cheap chic” made his own 5% pledge. Frederic de Narp joined Harry Winston Diamond Corp. from Cartier early this year, with the intention, he says, of marrying luxury retailing and doing good. Amidst a swishy gathering that included billionaires, actress Halle Berry (with de Narp, left), and more than $1 billion worth of diamonds on display, the 41-year-old Frenchman announced the launch of the Harry Winston Hope Foundation and an inaugural gift of $1 million to the Smithsonian.

The jeweler’s giving, de Narp says, will be directed at “changing lives through education.” He decided to give to the Smithsonian first because the Washington-based institution has owned the Hope Diamond since Harry Winston himself donated the world-famous gem in 1958. The deep-blue, 45.52-carat Hope Diamond was, appropriately, the surprise guest last evening — on display, protected by a security staff of a couple dozen.

Out on the red carpet, I chatted with Elie Wiesel, the renowned writer, Nobel Laureate, and Holocaust survivor. He told me that he has agreed to join the board of the Harry Winston Hope Foundation — even though he has, until now, turned down all other invitations to sit on boards, other than his own Wiesel Foundation.

Wiesel says he has such faith in de Narp, who cranked up philanthropic activities at Cartier, when he headed the U.S. business, but could do only so much since he wasn’t running the company. De Narp’s challenge today isn’t simply pledging to behave like one of the most generous CEOs on the planet. That’s easy. His real challenge is making the profits that will turn his 5% pledge into real money.

Harry Winston posted a net loss of $73.2 million on $412.9 million in revenue last year, and the stock, below $13, is way down from its pre-recession $40 range. While the dashing, publicity-savvy de Narp is on track to deliver profits this year, he’s a long way from minting millions to do good and please shareholders at the same time.