The most successful corporate campaign of all time?
How do you convince an entire society to buy into an idea?
A century ago, marriage proposals didn’t involve diamond rings. Today, more than 80% of first-time brides in North America receive one. The reason? One of the most sophisticated and enduring campaigns ever executed.
And that’s what I was thinking about this Valentine’s Day.
My wife and I are marking the day with a 9pm dinner (my fault for waiting until the day before to find a table). We’ll enjoy time without the kids, but I confess, this highly-commercial day always gets me thinking about moments in life that have been shaped by good campaigns. Especially moments that involve love.
Let’s take a look at how De Beers, with the help of a Philadelphia-based agency called N.W. Ayer & Son, sold an idea that reshaped society.
It offers lessons for anyone working in public affairs today.
The Great Depression and a Groundbreaking Advertising Agency
We need to go back in time nearly a century. The late 1930s was a brutal time for the diamond industry. The Great Depression had cratered demand for luxury goods. Diamond sales were tanking. Between 1919 and the late 1930s, the total amount of diamonds sold in America, measured in carats, declined 50%.
Compounding matters, there was an overabundance of supply which threatened to expose an uncomfortable truth: diamonds weren’t actually rare. They were valuable only because De Beers controlled the market and kept it that way.
In other words, it faced an existential threat: collapsing prices and consumer indifference. Which is why it turned to advertising agency, N.W. Ayer & Son.
Based in Philadelphia, N.W. Ayer & Son is widely regarded as the first full-service advertising agency in the United States.
Founded by Francis Wayland Ayer at the age of 21 with a $250 investment from his father (after whom he named the agency), it became the largest advertising agency in the country by 1890. If you work in the agency world, you can thank N.W. Ayer & Son for some of the innovations we take for granted today, like “open contracts”, in-house art departments, full-time copywriters, and the use of national market surveys.
The agency would eventually create some of the most memorable advertising slogans in history, including:
“Reach out and touch someone” for AT&T (1979)
“Be all you can be” for the U.S. Army (1981)
“When it rains it pours” for Morton Salt (1912)
“I’d walk a mile for a Camel” for Camel cigarettes (1921)
But before some of those famous campaigns, N.W. Ayer & Son got a call from De Beers in 1938. The mission? Not to just increase sales, but to make buying diamonds a cultural imperative. Specifically, N.W. Ayer & Son developed a comprehensive strategy to:
1. Create an emotional association between diamonds and “eternal love.”
2. Target the middle-class consumer market.
3. Focus on long-term market growth rather than short-term sales.
4. Educate consumers about diamond quality and value.
5. Use various marketing channels to reach a wide audience.
This approach was brilliant in its simplicity: create an emotional connection between diamonds and love, and make the public believe that real love requires a diamond ring. In other words, this approach was all about social engineering. And for that, they needed Hollywood.
Going to Hollywood and High Schools
Rather than hammer consumers with direct sales messages, N.W. Ayer & Son embedded diamonds into the cultural zeitgeist by making sure movie stars wore diamonds both on and off the screen.
They planted stories in newspapers and magazines about glamorous engagements—always emphasizing the size and sparkle of the ring. They even recruited etiquette experts and fashion influencers to reinforce the idea that a diamond engagement ring wasn’t just desirable—it was expected.
But a brilliant strategy only works if you get it in front of the right audience. That’s where high schools came in.
In a brazen move, they targeted young women long before marriage was in the picture. Ayer arranged for high school lectures where girls were indirectly taught that a man’s love was measured in carats. The campaign made diamond engagement rings a “psychological necessity,” embedding them into culture long before marriage was even a thought.
The Salary Rule
As the cultural shift gained momentum, De Beers expanded its strategy, introducing the concept of the "salary rule," which subtly suggested that a man should spend at least one month’s wages—later increased to two or even three—on an engagement ring. This transformed buying a diamond into not just an emotional gesture, but a financial and social expectation.
But they were far from done.
How can you ensure the value of these diamonds grows while you’re simultaneously convincing every aspiring groom to buy one?
How about a slogan that reframes what a diamond is.
That’s when Frances Gerety, a copywriter at N.W. Ayer, came up with four simple words that would fundamentally reshape consumer behaviour: A Diamond Is Forever.
A Killer Slogan to Kill the Resale Market
“A Diamond is Forever.”
Four simple words that drive home an important message: If a diamond is forever, then it should never be resold.
That was crucial. De Beers didn’t just want people to buy diamonds; it needed to kill the resale market. If people started selling their diamonds, it would expose another uncomfortable truth: that diamonds don’t actually appreciate in value.
By convincing people that a diamond should be cherished forever, it ensured that demand for new diamonds would never wane. It’s genius. And it’s a reminder that the best campaigns don’t just sell products or politics—they reframe how people think.
What I find interesting about the timeline of this slogan’s creation is this: it was developed in 1947, nine years after the agency was originally hired. Nine years! It speaks to a level of patience and commitment to the long-term strategy that is so hard to find in the public affairs world today.
A Multi-Decade Campaign
As we noted above, this campaign wasn’t just about selling diamonds — it was about embedding diamonds into the fabric of relationships, culture, and social expectations. Here’s a deeper look at the multi-decade approach N.W. Ayer implemented on De Beers’ behalf.
Iconic Slogan: In 1947, they created the slogan “A Diamond is Forever,” encapsulating the idea of eternal love while eliminating the resale market.
Multi-Channel Marketing: The campaign leveraged print advertisements, celebrity endorsements, and product placement in Hollywood films to normalize diamond engagement rings.
Educational Content: They developed materials about the 4 Cs (Cut, Carat, Color, Clarity) of diamonds, teaching consumers how to value diamonds—and reinforcing the idea that bigger and clearer meant better.
Native Advertising: Due to legal restrictions, ads were created without mentioning De Beers, effectively pioneering native advertising that blended seamlessly into editorial content.
Celebrity Endorsements: Ayer arranged for movie stars and socialites to wear diamonds at high-profile events, generating organic publicity and setting new luxury standards.
Market Research: Extensive consumer perception studies allowed the campaign to evolve over time, ensuring the messaging stayed effective.
Price Anchoring: The introduction of the “two-months-salary” rule created a benchmark for engagement ring spending, making the purchase feel like an obligation rather than a choice.
Targeting Different Demographics: Recognizing the need for continued sales beyond engagements, De Beers created the “eternity ring” to market to married women as a symbol of ongoing commitment.
Global Expansion: Similar campaigns were launched in other countries, each adapted to local cultural norms and economic conditions, ensuring diamonds became a universal symbol of love.
Lessons for Today’s Public Affairs Campaigns
How does the diamond playbook apply to shaping public opinion, influencing regulation, or shifting entrenched narratives? Three key takeaways:
1. Sell the Idea, Not the Policy
De Beers didn’t market diamonds—they marketed commitment. They transformed a raw material into a symbol so powerful that it became inextricable from one of life’s biggest moments.
The lesson?
If you want to influence public opinion, don’t push the policy—push the why.
Make people believe your issue is tied to something bigger than itself.
The most successful campaigns don’t just win arguments; they change minds.
2. Use Cultural Institutions as Leverage
Hollywood, high fashion, etiquette experts, even high school teachers—De Beers recruited them all to embed diamonds into public consciousness.
The same principles apply today.
If you’re trying to move public sentiment on climate policy, healthcare reform, or corporate governance, you need trusted voices carrying your message.
Politicians and CEOs are expected to advocate for their positions. But when cultural figures and unexpected influencers do it? That’s when narratives shift, and momentum builds.
3. Make the Alternative Unthinkable
De Beers didn’t just promote diamond engagement rings—they erased the alternative. By the 1950s, proposing without a diamond wasn’t just unusual—it was cheap. The campaign didn’t just sell diamonds; it created social pressure to conform. Love it or hate it, it’s impressive.
In other words…the most powerful campaigns don’t just persuade.
The best public affairs campaigns do the same. They don’t just persuade—they eliminate the alternative. They make the choice feel inevitable. They make people believe they always thought this way.