DUBAI- Natural diamond supply has peaked and will remain stable for the next few decades, the CEO of mining giant De Beers told Reuters on Monday, adding that the industry should see decent medium- to long-term growth.

De Beers Group, Anglo American's diamond business, is one of the world's leading diamond miners alongside Russia's Alrosa .

"I don't see a reason to think there will not be decent growth medium- to long-term in the diamond industry ... I feel more positive about the future than I have done for a long time," Bruce Cleaver said on the sidelines of a diamond industry conference in Dubai.

"Supply will remain stable. It won't fall off a cliff. We see 20, 30, 40 years of stable supply. That's why I feel quite positive," he said, adding that supply probably peaked in 2018-19.

The COVID-19 pandemic disrupted the global diamond supply chain, with some mines shuttered, rough diamond trade plummeting and polishers in India leaving their jobs.

In the second quarter of 2020, De Beers sold around 3% of the rough diamonds they would normally, Cleaver told the conference, partly because concerns about miners working closely together limited production and partly because buyers anticipated lower consumer demand as economies slowed.

When demand rallied from the end of 2020, increased polished prices led to increased rough prices, Cleaver told Reuters.

De Beers sales were $4.82 billion in 2021, up from $2.79 billion in 2020, company data shows.

In December, De Beers said it had applied to conduct exploration activities in north-eastern Angola, following reforms of the country's diamond industry.

"We remain extremely focused on exploration," Cleaver said, adding the company is exploring in Botswana, Canada and South Africa.

Last year, it also commissioned a survey of the ocean floor off Greenland's coast in a first step to determine whether it could hold deposits of highly-prized marine diamonds. De Beers already produces diamonds from Namibia's sea bed. 

"It is far too early to tell whether that is or isn't going to work," Cleaver said of the Greenland research.

De Beers' future will also see investment in Environmental, Social and Governance (ESG) practices, Cleaver said, without giving figures. This includes diamond traceability using blockchain technology, working towards a goal of being carbon neutral by 2030, and better mining practices.

(Reporting by Lisa Barrington; editing by Barbara Lewis) ((lisa.barrington@thomsonreuters.com;))