Global auction house, Sotheby's, owned by French-Israeli billionaire, Patrick Drahi, is preparing to auction a rare 28.88-carat diamond from Africa's richest mine in Botswana, with an estimated value of $2.8 million.

The stone, recovered from Botswana's Jwaneng Mine and produced by De Beers, Africa's largest diamond producer by value, carries an estimated top price of $2.8 million ahead of its scheduled sale on April 23 during Sotheby's luxury week in Hong Kong.

Named the "Jwaneng 28.88," the diamond is round, D-colour, and internally flawless, placing it among the rarest categories of polished stones. It will be offered as part of Sotheby's Hong Kong luxury sales, the auction house said.

According to Rapaport, the gem was cut from a 114.83-carat rough diamond, with De Beers' master cutters spending months refining it into its final form. The process reflects the increasing technical sophistication required in high-end diamond production.

"The Jwaneng 28.88 is a perfect emblem of De Beers' unmatched legacy in diamonds," said Quig Bruning, head of jewels for the Americans and Europe, the Middle East and Africa (EMEA) for Sotheby's. "It's at once a vanishingly rare feat of nature, combined with a master class in diamond-cutting and polishing."

Founded in 1744, Sotheby's is one of the world's oldest and largest auction houses. In 2019, French-Israeli billionaire Patrick Drahi acquired the company for approximately $3.7 billion, taking it private after decades of public trading. The firm is now headquartered in New York City, with offices and auction operations spanning major global markets. In recent years, minority stakes have been acquired by investors including a sovereign wealth fund from Abu Dhabi.

The auction comes shortly after another major discovery in Botswana, where Canadian miner Lucara Diamond Corp uncovered a rare 36.92-carat blue diamond. The stone is classified as Type IIb, a highly sought-after category known for its blue colour and exceptional market value.

However, the discovery comes at a challenging time for the diamond industry in southern Africa, where demand for natural diamonds has softened in recent years.

Botswana, the world's leading diamond producer by value, has faced pressure on sales due to weaker global demand and growing competition from lab-grown diamonds, which are cheaper and increasingly popular with consumers.

Business Insider Africa recently reported that S&P Global Ratings downgraded Botswana's long-term sovereign credit rating from BBB to BBB-, citing the prolonged downturn in diamond demand. The agency warned that the country's mineral-dependent economy could face sustained pressure, with foreign exchange reserves falling to $3.8 billion by the end of 2025, down by $3.7 billion from 2017 levels.

The diamond sector traditionally contributes about one-third of government revenue and roughly 70% of export earnings, making Botswana particularly vulnerable to fluctuations in global diamond prices.

Despite these challenges, Botswana remains one of the world's leading sources of premium stones, with the Jwaneng mine widely regarded as the richest diamond mine by value globally. Ahead of the sale, the diamond was showcased in London as part of an exhibition marking De Beers' 100-year cultural impact, reinforcing the brand's influence on the global jewellery industry.