Experts have welcomed the signing of a long-delayed rough diamond sales agreement between Botswana and South African mining giant De Beers. Representatives of the Botswana government and De Beers put pen to paper Tuesday on a 10-year deal following six years of negotiations.

Under the new agreement, Botswana will keep 30% of rough diamonds mined from a joint venture between the government and De Beers, up from 25% under the previous deal.

In the following five years, Botswana’s share of the stones will rise to 40%. Meanwhile, De Beers’ mining licenses in Botswana have been extended to 2054.

Local economist Keith Jefferis said concluding the deal was critical to the global diamond industry.

“[It is] a very positive move that the deal has finally been reached,” Jefferis said. “It will certainly help to bring some certainty to the global diamond industry. Overall, it’s a good deal for Botswana. To me, the most important part of that is the agreement that extends mining leases up to 2054 for the major mines, that is Jwaneng and Orapa [mines.]"

President Duma Boko, speaking at the contract signing, said Botswana made a good deal.

"We are happy,” Boko said. “We have traveled a long path of negotiations, and I have said, I have continued to maintain, that when you negotiate, you know that you have achieved a reasonable, equitable and fair outcome when all the parties to the negotiation come out of the negotiation crying and celebrating in equal measure."

Diamonds are the cornerstone of Botswana’s economy, accounting for around 80% of total export revenues.

De Beers chief executive Al Cook said under the new contract, the diamond company will invest an initial $75 million in a diamond for development program.

Cook emphasized Botswana and De Beers will work together to market the precious stones.

"Key to the partnership that we are agreeing today is a marketing partnership, a partnership for the first time,” he said, “putting the resources, the brains, the capabilities of the Botswana government together with the brains, the people of the resources of De Beers, a marketing partnership that can tell the story of diamonds of Botswana."

The Kimberley Process Civil Society Coalition is an umbrella body that observes the global diamond trade to prevent the sale of so-called blood diamonds.

Coalition coordinator Jeff Bamenjo said the signing of the deal is welcome but must bring tangible gains to the communities where the diamonds are mined.

"We have always said when diamonds are exploited, we expect benefits for the country and also for the local community,” Bamenjo said.

The newly signed agreement comes as the diamond industry reels from a global slump in sales, amid sanctions on stones mined in Russia, the world’s largest producer.