The Rock That Was Never Rare

It's Friday, March twenty seventh, and welcome to HigherIQ. If you've ever bought or received a diamond engagement ring, you probably believed three things: that diamonds are rare, that they're a timeless symbol of love, and that spending two months' salary on one is normal. All three of those beliefs were invented by a single company's marketing department. In 1869, an eighty three carat diamond was found near the Orange River in South Africa. It triggered a diamond rush. Thousands of prospectors flooded into what would become the city of Kimberley, staking claims on patches of ground barely bigger than a parking space. Among them was an eighteen year old Englishman named Cecil Rhodes, who had been sent to South Africa for his health. He didn't start by mining. He started by renting water pumps to the miners who did. With the profits, Rhodes began buying claims. One by one, then in bulk. Funded by the Rothschild banking family, he spent the next seventeen years consolidating every diamond mining operation in South Africa under a single company. In 1888, he founded De Beers Consolidated Mines. By 1890, De Beers was the sole owner of virtually every diamond mine in the country and had negotiated an agreement with the London Diamond Syndicate to sell a fixed quantity of stones at a controlled price. The agreement worked exactly as designed. During a price slump in 1891, De Beers simply reduced supply. The price held. Rhodes understood something that would define the diamond industry for the next century. Diamonds aren't actually rare. They're one of the most common gemstones on Earth. Emeralds, rubies, and sapphires are all geologically scarcer. What makes diamonds expensive is controlled supply. If every diamond that's been mined were released onto the market at once, the price would collapse. Rhodes's entire business model depended on making sure that never happened. "Our only risk," he told shareholders in 1896, "is the sudden discovery of new mines, which human nature will work recklessly to the detriment of us all." After Rhodes died in 1902, Ernest Oppenheimer took control of De Beers and tightened the monopoly further. Through a division called the Central Selling Organisation, De Beers bought diamonds from producers worldwide and controlled how many reached the market. If an independent mine tried to sell directly, De Beers would flood that segment with identical stones to crash the price, then buy the mine at a discount. If a country discovered diamonds, De Beers would negotiate exclusive purchasing agreements. At its peak in the late 1980s, the company controlled eighty to ninety percent of the global rough diamond supply. But controlling supply only works if demand stays high. And demand for diamonds wasn't always what it is now. In the 1930s, fewer than ten percent of American engagement rings contained diamonds. The Great Depression had crushed the luxury market. Young couples were proposing with rubies, sapphires, or no ring at all. De Beers needed to change that. In 1938, the company hired N.W. Ayer and Son, a Philadelphia advertising agency, with a specific assignment: make Americans want diamonds. The agency didn't run traditional ads at first. They planted stories in newspapers and magazines about celebrities wearing diamond rings. They lent diamonds to socialites and movie stars for the Academy Awards and the Kentucky Derby. They created the concept of the Four C's, cut, clarity, color, and carat, which turned diamond buying from a simple purchase into an educational experience that made people feel sophisticated. Then, in 1947, a young copywriter named Frances Gerety was finishing a late night at the office and realized she had forgotten to write a signature line for the new De Beers campaign. Exhausted, she scribbled four words on a scrap of paper and went to bed. The next morning, she showed it to her colleagues. Nobody was impressed. The line was "a diamond is forever." It became the most successful advertising slogan of the twentieth century, as named by Advertising Age. It has appeared in every De Beers engagement ad since 1948. Within two years of the campaign's launch, diamond sales in the US increased fifty five percent. By 1990, eighty percent of first-time brides received diamond engagement rings, up from ten percent in 1940. The tradition that feels ancient is less than a hundred years old. De Beers didn't discover a market. They built one. The company didn't stop at the engagement ring. When that market started to plateau, De Beers invented the anniversary diamond. "Marry me sounds so much better than just Merry Christmas," one ad read. They created the eternity ring, the journey pendant, the right-hand ring. Each new product came with its own emotional narrative designed to create another reason to buy a diamond. And then there was the price anchor. The "two months' salary" guideline for an engagement ring isn't a tradition. It's a line from a 1977 De Beers commercial. A black and white film of a couple on a beach, the only color being the gold solitaire ring, and a narrator asking: "How else could two months' salary last forever?" The number was arbitrary. It was marketing. And it became a social norm that millions of people still follow without knowing where it came from. The monopoly started cracking in the 1990s. Russia, which had been selling its diamonds through De Beers since the 1950s, severed the relationship as the Soviet Union collapsed. Australia's Argyle mine, once the largest in the world, left the cartel to sell independently. Canada opened new mines with no De Beers ties. By 2000, De Beers' market share had fallen from ninety percent to about sixty. In 2004, the company pleaded guilty to price fixing in the United States and paid a ten million dollar fine. By 2012, it settled class action lawsuits for nearly three hundred million dollars. And then came the real threat. Lab-grown diamonds are chemically, physically, and optically identical to mined diamonds. A gemologist can't tell them apart without specialized equipment. In 2018, a one carat lab-grown diamond cost about four thousand two hundred dollars at wholesale. By 2025, the same stone cost about a hundred and sixty eight dollars. That's a ninety six percent price decline in seven years. Lab-grown diamonds now account for forty five percent of the bridal jewelry market. Chinese and Indian manufacturers have scaled production so aggressively that producers are now making diamonds for less than ten dollars per rough carat. De Beers' response has been revealing. In 2018, the company launched Lightbox, its own lab-grown diamond brand, priced at eight hundred dollars per carat. The message was deliberate: lab-grown diamonds are fine for fashion jewelry, but they're not real luxury. The subtext was that if De Beers could cheapen the perception of lab-grown stones, it could protect the price of mined ones. It didn't work. Lab-grown prices kept falling. Lightbox prices fell with them. In 2025, De Beers announced it was shutting Lightbox down entirely and refocusing on marketing natural diamonds. The company that spent a century convincing the world diamonds are rare is now spending millions trying to convince the world that lab-grown diamonds, which are identical, don't count. Meanwhile, De Beers' parent company, Anglo American, has written down the value of De Beers by four and a half billion dollars over the past two years and is actively trying to sell the business. Natural diamond prices have fallen roughly forty percent since 2022. De Beers posted a loss of a hundred and eighty nine million in the first half of 2025. The company cut production by more than a third. The monopoly is over. The marketing worked for eighty years. The geology is catching up. So if this comes up in conversation, here's how to think about it. Diamonds aren't rare. The engagement ring tradition was manufactured by an ad campaign in 1938. "A diamond is forever" was written by a tired copywriter who didn't think it was any good. The two months' salary rule was a line from a commercial. And the company that built all of it is now losing billions because a lab can make the same stone for ten dollars. The longest-running marketing campaign in modern history is unwinding in real time, and the product it sold was never what they told you it was. Stay informed, stay curious, and we'll see you tomorrow.