(IDEX Online) - De Beers boss Bruce Cleaver says India could lose out to China and Thailand if diamond cutting does not resume soon. The CEO echoed the message of an open letter he penned earlier this week, in which he said the supply of rough diamonds must flow freely again as soon as possible.That puts him starkly at odds with industry leaders in Surat, who have asked for a month-long voluntary ban on rough diamond imports.Mr Cleaver (pictured) told India's Economic Times newspaper: "There are other places where polishing is done on a smaller scale like southern Africa. There are other diamond polishing centres like China and Thailand."He cautioned that midstream customers were smart enough and flexible enough to look elsewhere.Diamond factory bosses have been urging the Indian government to allow a partial return to work after the nationwide lockdown was again extended, to 17 May.But the nature of cutting and polishing would make it impossible to observe social distancing rules.India's Gems and Jewellery Export Promotion Council (GJEPC) says customers are beginning to cancel their orders and go to other markets.In his open letter Mr Cleaver said production and sale of rough diamonds should be allowed to resume freely as soon as possible, without external intervention.