(IDEX Online) - Surat's diamond industry remains at a standstill after another surge in COVID-19 cases.The city's 5,000 factories had been due to re-open yesterday after a two-week closure.But the Surat Diamond Association is urging all diamond units, markets and safe vaults to remain closed until 19 July at the earliest to prevent further infections.Surat Diamond Association president Babubhai Katheriya said: "We had to take this decision as a large number of diamond polishers and traders, especially from Varachha and Katargam zones, tested positive. "This voluntary lockdown will bring down the cases in Surat. Further decision will be taken after July 19."So far 600 diamond workers have tested positive for the virus.The plea to stay closed comes as India's polished diamond exports for June fell 41 per cent year-on year to $931m, according to figures released by the Gem and Jewellery Export Promotion Council (GJEPC).Increasing numbers of migrant workers are returning to their Gujurat villages because there is no work for them and the rise in coronavirus cases shows no signs of slowing.