The company, which is under sanctions linked to the Russian invasion of Ukraine, found the diamond at the Mayat mine in Yakutia. The stone is of non-standard shape and bordered by a yellow-brown halo, the company said in a statement on Sunday. It’s the largest gem-quality diamond mined in Russia since 2013.“A combination of mass, shape and color makes the stone unique,” Alrosa said in the statement.

State-controlled Alrosa, which produces about the same amount of gems as industry leader De Beers, has in recent years focused on cutting and marketing its largest gems in international auction houses, including Christie’s. Sanctions imposed by countries including the US and UK, prohibiting the import of Russian gem-quality diamonds, could hamper any potential sale of the newly recovered stone. Attempts to stop the sale of Russian gems in Europe have met resistance from importer nations like Belgium, who argue doing so would just shift the trade elsewhere. But there is growing speculation that G-7 nations — Canada, France, Germany, Italy, Japan, UK and US — and the EU will announce further restrictions this month.Alrosa’s sales took a hit after US sanctions were first announced, but recovered by shifting volumes to Asia, mainly India.