(IDEX Online) - The United States has announced further measures against Alrosa - but has not sanctioned diamonds mined in Russia but cut and polished elsewhere.Alrosa, one-third owned by the Russian government, has been placed on on the Specially Designated Nationals (SDN) list, blocking it from the US banking system and banning it from trade with individuals or companies in the USA."These sanctions will continue to apply pressure to key entities that enable and fund Russia's unprovoked war against Ukraine," said Brian Nelson, Under Secretary of the Treasury for Terrorism and Financial Intelligence.A group of congressmen are calling for more effective sanctions to close the loophole on polished diamonds.They say current restrictions, announced on 11 March, will have a negligible effect because they only prohibit the importation of rough diamonds, not gems that have been cut and polished outside Russia.The new restrictions, announced yesterday, also outlaw entities which are more than 50 per cent owned by Alrosa. They do not cover Angolan diamond production firm Catoca (pictured), in which Alrosa has a 41 per cent stake.We have approached Alrosa for comment.