Five of the 27 countries said the EU must stop importing diamonds from Russia, as the EU prepares new sanctions against Moscow for waging war against Ukraine.
The EU, which has implemented six rounds of sanctions since Russia invaded Ukraine on February 24, needs unanimity to agree any such ban that Belgium -- home to the world's biggest diamond trading hub Antwerp - has rejected in the past.
The bloc was spurred into action after President Vladimir Putin ordered a partial military mobilisation last week and moved to annex parts of eastern Ukraine.
The EU's executive European Commission is expected to present a formal proposal for more sanctions to member states this week.
Poland, Ireland, Lithuania, Estonia and Latvia proposed a ban on imports of diamonds from Russia, where Alrosa is the world's largest producer of rough gems.
The Antwerp World Diamond Centre said the sanctions would take away some 30 per cent of business and benefit rival trade hubs, giving clients the freedom to decide if they wanted Russian gems.
Belgium's foreign ministry and diplomatic representation to the EU did not respond to requests for comment.
On Sep 14, Prime Minister Alexander de Croo told an international diamonds conference that a ban would be a huge loss and would hurt an industry that accounts for 5 per cent of Belgium's exports and supports some 30,000 jobs.
An EU official and diplomat involved in preparations of new measures against Russia said that Belgium was now expected to lift its veto.
Following the Commission's proposal on new sanctions, diplomats and ministers will negotiate until they reach consensus, failing which the matter goes to the 27 national leaders when they meet in Prague on October 6 -- 7.