The mine's production had been suspended since January 13 for a 14-day lockdown ordered by the government of the Kingdom of Lesotho (GoL).
Lucapa did not indicate if any cases at the mine had been recorded, but confirmed that both mining and treatment options are online now that the order has been lifted.
"With the diamond market continuing its strong momentum into 2021, we look forward to the remainder of the quarter and completing the expansion project on time," managing director Stephen Wetherall said.
Lucapa Diamond and the GoL jointly hold the Mothae operation, which commissioned its mine and plant in late 2018, with 70% and 30% positions, respectively. Mothae is located in Lesotho's diamond-rich Maluti Mountains.