Mr Mugabe accused the companies of “swindling” and “smuggling” in an interview with state-run ZBC TV.
The 92-year-old leader denied that the move would affect relations with China, a major investor in the sector.
Zimbabwe was the world’s eighth largest diamond exporter in 2014.
“We have not received much from the diamond industry at all,” Mr Mugabe said, complaining that Zimbabwe had received $2bn (£1.4bn) from an estimated $15bn (£11bn) of revenues.
Mr Mugabe was also critical of Zimbabweans’ role in the alleged theft, saying that those “expected to be our eyes and ears have not been able to see or hear what was going on”.
Foreign mining companies can only operate in Zimbabwe as part of a joint-venture with local partners.
Last month companies operating in the Marange diamond fields were ordered to stop working after their licences expired.
Reports of abuse, including killings by the army, led to an international ban on diamond exports from Marange between 2009 and 2011.
Mr Mugabe dismissed any possibility of a diplomatic rift with China over the new policy, saying that he had personally complained to President Xi Jinping about the poor deal Zimbabwe was getting from its joint ventures with Chinese mining companies.
Chinese-run Anjin Investments, along with several other foreign mining operators, have reportedly challenged the new government orders in court.
Zimbabwe’s economy has struggled since a government programme seized most white-owned farms in 2000, causing exports to tumble.