Johannesburg - Diamond miner De Beers on Tuesday reported diamond sales of $3.5bn for the half year to end June 2011 - up 33% from the same period last year, and De Beers' highest ever sales figure recorded for the first half of the year.The group said this was driven by price growth of approximately 35%, buoyed by continued retail demand from the Indian and Chinese consumer markets and stronger than expected demand in America.It reported record EBITDA of almost $1.2bn - a 55% increase over 2010's $762m, reflecting the impact of excellent price growth during the period.Carats recovered during the period amounted to 15.53 million, in line with the first half's 15.43 million carats, and reflecting the impact of maintenance and asset management difficulties and, to an extent, excessive rainfall in southern Africa.It reported free cash flow of $469m - a reduction of 24% on last year due to the timing of stock purchases in the current period compared with 2010.The group noted that sales during the period have been exceptional, driven mainly by continued growth in the Middle East, Indian and Asian retail markets and their impact on rough price growth."De Beers has continued to focus on efficiency improvements and on maintaining a lower sustainable level of overhead base, which has resulted in a favourable impact on the bottom line."Looking ahead, De Beers said despite the ongoing turmoil with the global economy, it is encouraged by the continued strong growth in price and demand during the first six months of 2011."De Beers is confident that the exceptional growth in retail markets in India and Asia will continue to drive demand for diamonds. Reports from the recent JCK trade show indicate that the all-important Christmas season in the US, and Diwali, are set to be strong."