Last Updated: April 2026
TL;DR:
- By 1890, Cecil Rhodes had merged competing mines into one company controlling roughly 90% of global diamond production — one of the tightest commodity monopolies in modern history.
- The slogan “A Diamond is Forever” was written in 1947 by 24-year-old copywriter Frances Gerety and launched in 1948; Advertising Age later named it the top ad slogan of the 20th century.
- The empire is cracking in 2026: lab-grown diamonds now account for 52% of US engagement ring center stones (up from just 3% in 2018), and parent company Anglo American has booked over $5 billion in De Beers-related impairments in the past two years.
Every diamond engagement ring sold today traces back to a marketing decision made in 1947, not a romantic tradition from centuries past. I’ve cut and set thousands of diamonds over my career, and I still get asked why a “tradition” that feels ancient is actually younger than the microwave oven. The short answer: De Beers built the entire idea from scratch, and it worked better than any ad campaign in history. Here’s how a failed cotton farm turned into a 150-year diamond empire — and why that empire is losing ground fast.
When Did De Beers Start Controlling the Diamond Market?
De Beers began consolidating power in 1888, when Cecil Rhodes merged rival Kimberley mining operations into De Beers Consolidated Mines. By 1890, the new company controlled an estimated 90% of global diamond production, giving it near-total power over price and supply for the next century.
The story starts in 1871 on a farm that couldn’t grow cotton. Cecil Rhodes, then 17, had moved to South Africa with his brother Herbert to escape a lung condition and try farming in the British colony of Natal. The land failed as cropland. What nobody realized yet was that it sat on top of one of the richest diamond deposits on earth — first hinted at when a 15-year-old named Erasmus Jacobs picked up a 21.25-carat stone on the banks of the Orange River years earlier, not knowing what it was.
Rhodes and his brother caught “Diamond Fever” and started mining near Kimberley, in an area then nicknamed the New Rush. Before digging themselves, they rented out water pumps to other miners — a low-risk business that funded Rhodes’ first land purchases. He later bought claims from two brothers, Diederick and Johannes De Beer, devout Christians who wanted no part of the diamond rush and simply sold their land.
Diamonds have physically existed for more than 3.3 billion years, formed roughly 150km underground before volcanic activity pushed them toward the surface. Supply was never the industry’s problem — oversupply was. When too many mines flooded the market at once, diamond prices crashed to the level of semi-precious stones like topaz. That collapse gave Rhodes the opening to buy out struggling mine owners and consolidate control.
How Cecil Rhodes Built a Diamond Monopoly
Rhodes formalized his control by founding De Beers Consolidated Mines in 1888, merging his holdings with competitor Barney Barnato’s operations. According to De Beers Group, this consolidation — plus a handful of shell companies — handed the new entity roughly 90% control of world diamond output by 1890.
Rhodes wasn’t just a mining executive; he was also Prime Minister of the Cape Colony, a dual role that showed up directly in business decisions. When a major diamond find in 1891 sparked a bidding dispute, the commission set up to decide the buyer favored De Beers — unsurprising, since Rhodes chaired both the company and the government reviewing the sale.
Rhodes died of a heart attack in 1902 at age 48, but the company he built kept growing under new leadership, eventually forming The Diamond Syndicate to regulate prices across the whole industry. Sir Ernest Oppenheimer, whose family’s Anglo American company became a major De Beers shareholder, later took the reins and ran the syndicate as a strict supply gatekeeper for decades. According to Sahil Bloom, Oppenheimer’s syndicate model was so tight that even independent mines had little choice but to sell through De Beers’ single distribution channel.
What Made the 4Cs System So Important?
In 1939, De Beers partnered with the Gemological Institute of America to formalize the 4Cs — carat weight, color, cut, and clarity — as the universal standard for grading diamond quality. That framework still determines diamond pricing today and gave De Beers a shared vocabulary to justify premium prices industry-wide.
Before the 4Cs existed, diamond value was largely a matter of a jeweler’s word. Standardizing the grading system did two things at once: it gave buyers a sense of objective quality control, and it gave De Beers a consistent way to steer perceived value upward. I still walk customers through these four factors every week, and carat weight is the one people fixate on — cut quality usually matters more for how a stone actually looks on the hand.
Why Did De Beers Launch “A Diamond Is Forever”?
De Beers launched the campaign in 1947-48 because diamond sales had dropped roughly 50% during the Great Depression and World War II, and most Americans viewed diamonds as luxury items for the wealthy, not something to save up for. The slogan reframed a diamond purchase as a permanent, non-negotiable symbol of love.
De Beers hired New York ad agency N.W. Ayer & Son back in 1938 specifically to solve this sales slump. The agency’s copywriter, Frances Gerety, wrote “A Diamond is Forever” in 1947, and the campaign rolled out in 1948. According to Sotheby’s, the tagline did something no prior ad had: it discouraged resale entirely, turning diamonds into a one-way purchase instead of a tradeable asset. That single idea is why the secondhand diamond market remains weak even now — my customers routinely ask why their diamond appraises for a fraction of retail, and this 1947 marketing decision is a big part of the answer.
Ayer’s strategy specifically targeted middle-income Americans who were spending their money on cars and appliances instead of jewelry. The campaign didn’t sell a specific ring — it sold an obligation. Within a decade, a diamond engagement ring went from a rich person’s indulgence to an expected step before marriage.
The Ad Campaign That Rewired an Entire Generation
The campaign’s timing mattered as much as its message. Europe was under threat of war, the American economy was still shaky, and De Beers needed buyers to think long-term about diamonds rather than treating them as a luxury purchase they could later resell. Ernest Oppenheimer’s tight control over global supply meant that whatever De Beers said about diamonds carried the weight of near-total authority — there was no competing narrative from another major supplier.
By the late 20th century, De Beers still held a commanding market position even after losing pieces of its monopoly to new mines discovered in Australia and Russia. In 2000, the company unveiled the De Beers Millennium Star, a 203.04-carat pear-shaped diamond and the second-largest top-color diamond ever found, cut specifically to maximize its visual impact. De Beers Jewellers launched as a standalone luxury brand the following year in 2001.
Diamond mines in Botswana, Namibia, South Africa, and Canada kept De Beers relevant well past its monopoly years, even as competitors chipped away at total market share. According to Britannica, De Beers’ share of the global rough diamond pipeline had fallen well below its historic 90% peak by the 2010s, though it remained one of the largest single producers on earth.
Is De Beers Still the King of Diamonds in 2026?
No — not the way it once was. Lab-grown diamonds now make up 52% of US engagement ring center stones, up from just 3% in 2018, and De Beers cut its official diamond prices in 2026 after three straight years of market decline. Parent company Anglo American has recognized more than $5 billion in De Beers-related impairments since 2024.
This is the part of the story most people researching a 2026 engagement ring actually need to know. The mined-diamond premium that De Beers spent a century building is being undercut by lab-grown stones that are chemically identical and cost 60-80% less at the same carat weight. Buyers who want that classic look but don’t want to pay the De Beers legacy premium have more leverage right now than at any point in the last 80 years.
What Tiger Learned From 150 Years of Diamond Marketing
Working the factory floor for two decades taught me one thing De Beers proved at scale: a stone’s price has never been purely about rarity. Diamonds aren’t actually rare — De Beers spent a century controlling supply precisely because there was too much of it. What made the ring valuable was the story wrapped around it, and that story was written by an ad agency, not a geologist. It’s the same reason resale prices on diamonds disappoint so many people after the wedding — the “forever” pitch was never about resale value.
If you’re shopping for a ring in 2026, that history should change how you buy, not just how you think. Ask what you’re actually paying for: the stone’s specs, or the century-old narrative stamped onto it. If it’s the latter, a lab-grown or moissanite alternative gets you the same look without funding a marketing legacy you never signed up for.
The Bottom Line
De Beers didn’t discover the diamond engagement ring tradition — it manufactured it, starting with a monopoly built by Cecil Rhodes in 1888 and cemented by a 1947 ad slogan that convinced the world diamonds equal love. That strategy worked for 80 years. It’s not working the same way in 2026: lab-grown diamonds control over half the US engagement ring market, and De Beers itself is cutting prices to survive. If you want the history without the markup, buy the stone on its actual specs — carat, cut, clarity, color — not the century-old slogan attached to it. Compare your options before you commit, whether that’s a natural stone, a lab-grown alternative, or a solid metal setting that will outlast any marketing trend.
Frequently Asked Questions
Did De Beers invent the engagement ring?
No. Engagement rings existed long before De Beers, including gemstone rings worn by European aristocracy for centuries. What De Beers actually invented was the idea that a diamond specifically — not any gemstone — was the required, non-negotiable choice, and that everyday middle-income buyers should save up for one.
What do the 4Cs mean for a diamond?
The 4Cs are carat weight, color, cut, and clarity — the grading system De Beers and the GIA formalized in 1939. Cut has the biggest visible impact on sparkle, while carat weight is simply the stone’s physical mass and often gets overweighted by buyers focused on size over quality.
Is De Beers still a monopoly today?
No. De Beers peaked at roughly 90% control of global rough diamond production in 1890 and held a dominant position for most of the 20th century, but new mines in Russia, Canada, and Australia broke that monopoly starting in the early 2000s. By 2026, De Beers is a major producer, not a market-controlling monopoly.
What is the De Beers Millennium Star?
The De Beers Millennium Star is a 203.04-carat pear-shaped diamond unveiled in 2000, ranked as the second-largest top-color diamond ever discovered. It was cut specifically to maximize brilliance and remains one of the most famous stones connected to the De Beers brand.
How much of the 2026 diamond market is lab-grown?
Lab-grown diamonds account for 52% of US engagement ring center stones as of 2026, up sharply from just 3% in 2018. That shift has pushed De Beers to cut its official diamond prices for the first time in over a year, after three consecutive years of market decline.
Stephanie is a jewelry lover when she was a teenager. Her major was fashion design when she was in college. She is a jewelry designer at SOQ Jewelry and other design companies. Now she is also a writer for our website. She writes a lot of designs&brands posts with very actionable tips.