Letseng had been put on care and maintenance for three weeks at the end of March 2020 following a government-mandated lockdown of all non-essential industries to address the COVID-19 pandemic. 

The small landlocked kingdom, within South Africa, went into a new, two-week lockdown from midnight on Wednesday due a surge in COVID-19 infections and deaths.

The government's move this week to risk mitigation colour code red included a 7pm-6am curfew, a ban on international travel with some exemptions, and super-spreader activities were restricted except essential goods and services.

The number of COVID-19 deaths jumped from 1 in the week ending January 2, to 20 the following week, with the country's cumulative death toll now at 87.

Gem said Letseng would continue to implement measures for the regular testing and protection of all of its mining staff and contractors, as required by law and in accordance with the strict health and safety measures which were put in place at the beginning of the pandemic.

"The health and safety of all of our employees and contractors remains paramount to Gem Diamonds and we shall continue with the testing and precautionary measures which have been effective at Letseng and our other operations during this pandemic," CEO Clifford Elphick said.

Gem had further reduced its debt position in the September quarter to end the period with a net cash position of US$1.1 million, in a tough year for the diamond market. 

The company said at the time the process to sell its Ghaghoo mine in Botswana remained subject to "certain suspensive conditions and regulatory approvals".

Its share price (LSE: GEMD) has fallen from 60p a year ago to last trade at 41.4p, capitalising it about £57 million (US$78 million).