Anglo American CEO Duncan Wanblad has acknowledged that De Beers and the broader diamond industry misjudged the threat posed by lab-grown diamonds, the Financial Timesreported Tuesday. “Looking in the rear-view mirror is a much more perfect science than trying to do it in real life,” he said. Anglo is trying to sell De Beers after writing down its value three times in the past three years. Wanblad said about a fifth of natural diamond supply is expected to leave the market within a year, with few operations returning. De Beers has paused output at its Venetia mine in South Africa and shut its own lab-grown brand, Lightbox.