An employee shows a rare 242-carat rough diamond, which will be offered at the 100th international auction of Russian state-controlled diamond producer Alrosa, during a presentation in Moscow, Russia February 25, 2021. The diamond is one of the biggest gem-quality stones Alrosa has mined this century, the company said. REUTERS/Tatyana Makeyeva

A view shows a rare 242-carat rough diamond, which will be offered at the 100th international auction of Russian state-controlled diamond producer Alrosa, during a presentation in Moscow, Russia February 25, 2021. Russian state-controlled diamond producer Alrosa will offer a rare 242-carat rough diamond - one of the biggest gem-quality stones it has mined this century. REUTERS/Tatyana Makeyeva

A rare 242-carat rough diamond, which will be offered at the 100th international auction of Russian state-controlled diamond producer Alrosa, is placed on scales during a presentation in Moscow, Russia February 25, 2021. The crystal-clear diamond is the size of a small egg. Alrosa, the world's largest producer of rough diamonds, competes with Anglo-American unit De Beers. REUTERS/Tatyana Makeyeva

An employee shows a large gem-quality diamond named by Russian miner Alrosa after Sputnik-V, a vaccine against the coronavirus disease (COVID-19), in Moscow, Russia February 25, 2021. The diamond was held back until now to mark Alrosa's 100th international auction. REUTERS/Tatyana Makeyeva

An employee shows a large gem-quality diamond named by Russian miner Alrosa after Sputnik-V, a vaccine against the coronavirus disease (COVID-19), in Moscow, Russia February 25, 2021.The auction price will start from $2 million. REUTERS/Tatyana Makeyeva

An employee shows gem-quality stones, including a rare 242-carat rough diamond that will be offered at the 100th international auction of Russian state-controlled diamond producer Alrosa, during a presentation in Moscow, Russia February 25, 2021. The diamond is one of the biggest gem-quality stones Alrosa has mined this century, the company said. REUTERS/Tatyana Makeyeva