De Beers, Cullinan and a legacy you might not know

South Africa’s diamond industry is a story of ambition, wealth, and heritage.

It began in either the late 1860s or early 1870s – history isn’t entirely clear – when a 21.25-carat diamond was discovered near the Orange River.

This sparked the Kimberley Diamond Rush and the creation of the “Big Hole,” one of the world’s richest diamond mines, setting the stage for South Africa to become a global diamond powerhouse.

Almost 150 years later, it seems that diamonds are no longer “a girl’s best friend” – at least not the ones dug from the ground.

Average rough diamond prices have fallen roughly 26% since 2022, reflecting weaker demand, inflationary pressures, and competition from lab-grown stones.

Diamond prices are closely tied to size, quality, colour, clarity, and market demand. Rough diamonds are graded and sold through tender sales, auctions, and contracts, often overseen by companies like De Beers – the company behind the iconic “diamonds are a girl’s best friend” tagline.

High-value stones, such as those from Petra Diamonds’ Cullinan Mine, still fetch millions. For example, a 299-carat Cullinan diamond sold for $12.18 million in 2025.

Smaller or lower-quality diamonds are often used for jewellery, but a large portion also serves industrial purposes.

Since about 2020, lab-grown diamonds have become widely used in both jewellery and industrial applications.

While iconic diamonds like Cullinan command top prices, the broader market faces declining prices due to competition from synthetic alternatives and shifting consumer preferences.

South Africa’s diamond heritage traces back to Cecil John Rhodes, a sickly Brit who consolidated control of the diamond sector in 1888 with the formation of De Beers Consolidated Mines.

The company went on to dominate global diamond supply for more than a century.

De Beers didn’t just mine diamonds; it shaped the world’s perception of them. Its campaigns made “A Diamond Is Forever” a household phrase immortalised by Marilyn Monroe’s declaration in Gentlemen Prefer Blondes that “diamonds are a girl’s best friend.”

The corporate story of De Beers has shifted dramatically in recent years.

Once an 85% Anglo American-owned giant, it has been spun off to allow Anglo to focus on its core commodities, following a $2.9 billion write-down.

De Beers now faces declining rough diamond sales, increased competition from lab-grown alternatives, and a market in which average diamond prices have fallen roughly 26% since 2022.

In 2024, the company reported $543 million in rough diamond sales, down from the previous year.

Premier Mine produced the Cullinan Diamond in 1905, the largest gem-quality rough diamond ever discovered at 3,106 carats.

Named after the mine’s owner, Sir Thomas Cullinan, the diamond was presented to King Edward VII and later cut into several stones, including the Great Star of Africa and the Lesser Star of Africa, now part of the British Crown Jewels.

Today, the Cullinan Mine, located in a quaint dorpie named after it, is owned by Petra Diamonds, which continues to produce some of the world’s rarest high-value diamonds, including coveted blue stones.

Tours above and below ground are offered at the mine amid tight security, complemented by tales of the town’s history, which itself feels somewhat lost in the midst of time.

Despite these challenges, the diamond industry remains a cornerstone of South Africa’s economic and cultural heritage.

Mines like Cullinan and Venetia provide employment, sustain local economies, and continue to contribute to the nation’s global profile.