Diamond buyer Elliot Tannenbaum, from the Leo Schachter Diamond Group, holds a bag of uncut diamonds at a sightholders week at De Beers offices in central London August 29, 2013. From November, the whole of the De Beers sales operation will move from the heart of London thousands of miles south to Gaborone, the capital of Botswana. Photograph taken on August 29, 2013. REUTERS/Olivia Harris (BRITAIN - Tags: BUSINESS COMMODITIES ENVIRONMENT)