During a recent Wharton Leadership Lecture, De Beers managing director Gareth Penny offered his audience a multimedia presentation about the international diamond company. It included a backdrop collage on the mining industry with pictures of workers, children and one diamond-drenched model, along with a three-minute film that promoted diamonds through the ages as “Tears of the Gods” (according to the ancient Greeks), “Splinters of Falling Stars” (so said the Romans) and, of course, “A Diamond Is Forever” (the marketing mantra and internationally famous advertising slogan of De Beers).

And while it was clear from the promotional props that diamonds have, in fact, been around forever (“before dinosaurs roamed the earth”), De Beers has not.…