Just as the world's largest diamond producer, De Beers, has landed back on its feet with a big jump in half-year sales, CEO Gareth Penny has announced that will step down from his position later this year. 

No word on why exactly Penny has decided to leave the company, but it's a surprising development as the group is heading into a better period since the global economic crisis harshly affected the world. 

Penny would only say to the media, "I feel it's the right time" and "We've come out of a difficult period." 

He headed De Beers for the past five years.

Penny will continue his reign as CEO until the end of September and then work part-time until the end of the year.

Currently CFO Stuart Brown and CCO Bruce Cleave are acting as joint-CEOs for the diamond group while De Beers finds someone to take his place.  Penny's actual successor has not yet been named.

Bloomberg interviewed Peter Davey, head of mining research at Ambrian Capital Plc, who said Penny's resignation will overshadow De Beers results, which are steadily improving, as well as results for the person who will eventually follow him. 

"Why let him step down if you haven't got a replacement? It's not an ideal situation," he said.

De Beers currently produces about 40 percent of the world's diamonds and can trace its history to 1888.  Its first-half sales of unpolished and uncut stones increased 84 percent to $2.6 billion.

Celebrities like football player Reggie Bush, socialite Kim Kardashian and music mogul Russell Simmons have all backed De Beers in the past.