UPDATE 1-Strong demand for diamonds, rough and smooth, boosts Alrosa sales Reuters 1 hr ago MOSCOW, May 12 (Reuters) - Russia's Alrosa, the world's largest producer of rough diamonds, said on Wednesday its April sales of rough and polished stones rose by 12% month-on-month to $401 million after demand for diamond jewelry strengthened in the main markets. Global demand for precious stones has been recovering from the impact of the COVID-19 pandemic since the second half of 2020. Sales by the state-controlled company totalled $1.6 billion for the first four months of 2021. At the height of the pandemic in April 2020, Alrosa's sales were only $15.6 million. They rose to $357 million in March this year.