Diamonds Aren't Forever
(And Neither is Your Love)
The wedding of Charles and Diana, (later the Prince and Princess of Wales), 29 July 1981 / Flickr

Diamonds Aren't Forever (And Neither is Your Love)

Rob Brooks
Rob Brooks
13 min read

Diamond is the most valuable, not only of precious stones, but of all things in this world.
~Pliny The Elder

Loving someone, and having them love you back, is the most precious thing in the world.
~Nicholas Sparks, The Notebook

At age 11, I first glimpsed the bewildering anthropologic spectacle that is the grand wedding. Along with 750 million others, I watched on television as Charles, Prince of Wales married Lady Diana Spencer. Friends and neighbours quaffed sparkling wine around their televisions mid-morning, revelling in the intoxication of two people they had never met promising to love, honour, and—in Diana’s case—obey one another until death rent them asunder.

From the moment they announced their engagement, a perfect media storm amplified the couple’s every move. Commentators gasped when Diana chose her own engagement ring from a selection presented to her by Garrard jewellers. Traditionalist lips pursed at the idea that the same design—a large oval sapphire surrounded by 14 round diamonds set in 18 karat white gold—could be ordered from the Garrard catalog by anyone who could spare a lazy £28,000.

No current celebrity understands the public appetite for engagement bling better than Kim Kardashian. First husband Kris Humphries put a 16-carat diamond on her finger in 2011. Kanye West proposed in 2013 with a 15-carat emerald-cut ring he co-designed. Later, he bestowed on Kim a “second engagement ring” of the same design, but this time sporting a 20-carat rock.

Beyoncé Knowles-Carter, herself the owner of 18 carats worth more than $5 million, once sang that a man who wanted “it”, should have put a ring on “it”. The “it” not being restricted to the fourth digit on a woman’s left hand. The association between diamond rings, matrimony, hetero sex, and the intention to spend one’s life with another provides a fascinating tale of economics, marketing, biology, and culture. And it teaches us about that which glitters more than gold and scintillates more than gems.

Diamond rush

The custom of mounting a gemstone in an engagement ring traces back only a few hundred years. Until the late 19th century, diamonds were rare. For millennia, the alluvial gravels of India’s rivers yielded modest numbers, most of which came to bejewel the subcontinent’s elites. As trade routes opened, diamonds trickled into the hands of European nobles who set them in jewellery, including rings.

Meagre supply and ballooning demand assured that the rare, beautiful stones grew ever more valuable. Then, in the arid furnace of South Africa’s North-West, in 1866, a farmer’s son found the 21-carat Eureka diamond. At the largest mine, in Kimberley, miners excavated more than 13 million carats—or 2,720 kilograms—of diamonds, flooding the market.

Recognising that competition and over-supply were dulling the diamond’s high-value sparkle, Cecil John Rhodes and Barney Barnato bought up all the claims and formed De Beers Consolidated Mines, soon controlling 95 percent of the world’s supply. De Beers sold uncut gems exclusively to a syndicate of 10 companies, controlling supply to keep prices high, and stockpiling diamonds against future increases in demand. For more than a century, De Beers ruled the market with an imperialist fist, leading to allegations of violence, political meddling, price-fixing and collusion.

Far from content to manipulate supply, De Beers mastered the creation of new demand by enlisting the N.W. Ayer agency to advertise diamonds in the USA. Their campaigns turned a modest trend for engagement rings set with small diamonds into an expectation that a ring should bear the biggest, best diamond an aspiring groom could afford. In so doing, copywriter Frances Gerety composed what became the greatest advertising slogan of the 20th century: “A Diamond is Forever.”

Around these four words, the agency built the diamond into a physical embodiment of every hope a betrothed couple holds for their love and their shared future: that it is precious, sparkling, and will outlast eternity. Since “A Diamond is Forever” debuted in 1943, the diamond engagement ring has become a near-universal seal of betrothal, even in societies that had never before used engagement rings.

Emboldened by their success, De Beers and Ayer contrived new “traditions.” They persuaded couples celebrating major wedding anniversaries to double down on their notions of “forever” by purchasing yet more diamonds. It doesn’t matter if the lucky owner doesn’t wear her jewels, as long as she hangs onto them. In fact, if she keeps them locked up and out of sight—except on the most special occasions—she makes them less visible, embellishing the appearance of rarity.

With all the diamonds mined, cut, polished, and sold since the Kimberley diamond rush, one might expect a vibrant re-sale market to undercut high prices. And yet the evoked connection between the gems and the longevity of one’s marriage creates a psychological obstacle that prevents diamonds from trickling back to market and elevating supply. Those that are resold fetch a meagre return. Kris Humphries only recovered $620,000 of his $2 million outlay, despite the celebrity lustre of the ring having graced Kim Kardashian’s finger during their engagement and 72-day marriage. When diamond sellers say “forever,” they mean both “until death us do part” and “never to be resold.”

Nothing lasts forever

Not only are diamonds not rare, they also prove far from indestructible. They chip, scratch, wear, and can burn to a cinder. In these flaws, diamonds crystallise into a far more apt metaphor for human romance than De Beers and Ayer could ever have imagined.

Fairytale weddings occupy such prominence in our imaginations because they sell the promise that romantic love can endure. Stories, from Cinderella and her Prince, to the anonymous couple who wed at Cana of Galillee, to the monumental love and 1612 marriage between Shah Jahan and Mumtaz Mahal, promise that a couple can find each other, fall in love, and live happily ever after. These stories have such power precisely because ample evidence from real life reveals that romantic love is neither one-in-a-million scarce, nor a permanent ever-fixed mark.

For all the regal spectacle of their wedding, Charles and Diana’s marriage proved as flawed as any other, ending in divorce after 11 years. The hopes that hundreds of millions of viewers invested as they watched the wedding on TV shattered against the banal reality that forsaking-all-others is much easier said than done, and until-death-us-do-part usually involves a very, very long time.

Royal and celebrity weddings might revolve around two flawed human beings exchanging very personal promises, but they are also part of a long-running cultural advertising campaign. Like “a diamond is forever,” this advertising campaign plays to deep insecurities about love, commitment, power, and the nature of sex. It mines one of the deepest and most ancient human insecurities: that the commitment a couple makes might prove a poor or foolish investment.

Big, expensive weddings promote the bundling together of romantic love, sex, and marriage. In the manner of a glossy advertising campaign, grand weddings conjure the impression that all three are precious, long-lasting goods of enormous value. Royal weddings, celebrity weddings, wedding magazines, and destination weddings all turn marriage into the kind of luxury product for which demand increases as the price rises, counter to the normal dynamics of supply and demand. Economists call these “Veblen goods” after Thorstein Veblen who first noted how consumers seek and signal status via conspicuous consumption.

One could search the entire human cultural repertoire and never arrive at a more perfect expression of conspicuous consumption than the grand wedding. A wedding can boost the status of the newlyweds and their families in a way that knows no equal. And each big wedding—the bigger, the fatter, and the more royal the better—elevates the status of other weddings, distant, recent, and soon-to-be.

Sex as a transaction

When a man asks a woman to marry him, and bestows on her a diamond ring, what does he get in return? A promise that at some mutually-agreed date they will begin a life of cohabitation, cooperation, and, perhaps, reproduction. But, as many a fiancé has no doubt asked himself, why does he lay out two months’ wages for a ring, whereas his fiancée does not? If they mutually wish to marry their fortunes together, then what renders the engagement so one-sided?

The blunt answer is that her sexuality has a value that his lacks. If that sounds stereotypical and sexist, that is because in this single fact lie the directions to the wellspring of most sexism, and much of the complexity and pain that besets human sexuality.

The disparate values in women’s and men’s sexuality are illustrated in what follows the breaking off of an engagement. Until a few decades ago, women in most Western countries could sue a man who reneged on an engagement for “breach of promise.” Women retained the prerogative to change their minds, probably because the implication that sex might have taken place stained a woman’s reputation and marriageability but did no such dishonour to the man. Implicit, although seldom acknowledged, is that women’s sexual consent embodies a form of power. A power women have long wielded to secure their future and perhaps achieve social mobility.

An engagement ring represented a man’s down-payment on the woman’s sexual and reproductive future. It remains customary for a woman to keep the ring if the man breaks off the engagement, ostensibly to compensate for the drop in her own value on the mating market. If she breaks things off, however, convention stipulates she should return the ring. In this case the man is the one left holding a good with much-diminished resale value. But these are merely manifestations of the different values of male and female sexuality within a Western, De Beers era, cultural and economic context. How general are the differences and how do they originate?

Gary Becker won the 1992 Nobel Memorial Prize for extending economic analysis to, among other things, human social living and sexual relationships. Becker, and the economists who followed, demonstrated that people exchanged sex for goods, labour, protection, loyalty, property, and even cash. Individuals compete within mating markets and “prices” are shaped by supply and demand.

According to the psychological principle of least interest, the party in a transaction with the greater stake in a particular outcome has less power, and must thus offer more in order to achieve that outcome, than the less-interested party. Psychologists Roy Baumeister and Kathleen Vohs argued that women, in higher demand as mates than men, have greater power over whether a given mating takes place. As a result of that power, heterosexual sex is largely a female-controlled resource.

Why are women generally in higher demand than men? To begin with, because pregnancy, breast-feeding, and menopause limit the time women spend in the mating market, rendering fertile women scarce relative to available men. That gives women power over mating decisions and compels men to trade. They bargain with their contributions to parenting, provision, protection, and the family’s status.

Women’s mating market power only begins with evolved physiological differences. Other demographic, cultural, social, economic, and biological factors change the nature and value of the sexual transaction. An understanding of those dynamics can take us a long way toward resolving why sex can be so complicated, such a well of shame, and a cause of such deep ideological divisions.

The price of sex

When demographic changes alter the ratio of women to men, they alter supply of and demand for heterosexual sex, shifting the balance of negotiating power toward the rarer sex. Whenever women outnumber men, competition among women rises, pushing prices down.

Even a small tip can loosen things up. Highly educated, single women in Sydney, where I live, bewail a severe man drought. Eligible bachelors revel in a relative scarcity that tilts the odds ever in their favour. Compared to many other cities, Sydney men don’t have to spend as much effort, money, or time wooing a woman before the deal is done. Women become more likely to have sex without commitment, and they do so earlier in the relationship than they otherwise would have.

When women outnumber men, marriage rates drop, uncommitted sex increases, and unintended pregnancies rise. More single women, many of them mothers, means women are more likely to have to work outside the home to support themselves. With more autonomy from men, and more women as the primary or only earner in the family, political pressure for equitable opportunities and pay tends also to rise. In short, many conditions that set social conservatives on edge tend to arise in female-biased—low price of sex—societies.

The opposite pertains when men outnumber women. Women, now in short supply, become more likely to marry, especially to high status men. The British created a dramatic example when they transported more than 150,000 convicts—over 85 percent of them men—to Australia between 1787 and 1868. Some areas had more than a dozen settler men per woman, whereas others retained remarkably even sex ratios. The more male-biased the sex ratio, the greater the proportions of women who married, and the fewer who entered paid employment. In general, even subtle increases in numbers of men, far smaller than those in convict-era Australia, turn the average partnered man into a more committed spouse and father. Competition among men effectively raises the price of sex.

Just as the price of diamonds is influenced by far more than the supply dug out of the mines, the price of sex is shaped by far more than the relative numbers of women and men. Cultural messages about sex, marriage, love, and relationships turn appearances of supply and demand into market-based reality. Laws that regulate who can marry whom, how couples can divorce, the property rights and child custody arrangements that follow divorce, and the rules around decency and sexual morality all grant supply and demand a hard edge.

As far back as written historic records extend, people sought to regulate sex, especially women’s sexuality and male homosexuality. From the Sumerian king Ur-Nammu, some 4,000 years ago, to the Romans and the Hebrews of the early Common Era, to Victorian England, religious and civil laws consistently suppressed the supply of sex—by people who might sleep with men—far more so than the demand from the men themselves.

Both the advent of farming and the establishment of city states sent the suppression of sex off the charts. But the anthropological record is rife with sexual double standards and suppression, even in societies that never farmed or lived in cities. In my recent book, Artificial Intimacy, I trace how technological changes, from ploughs to contraceptive pills to pornography—and soon to sex robots—consistently change the way women and men value one another as mates, and thus the price of sex.

Norms and expectations can have effects as powerful as the law. Cloistering, purdah, and preventing women going out in public without a male relative all conceal women from the public eye, generating impressions of female scarcity. Less extreme—but far more pervasive—modesty ideals exert similar effects. Public battles over Islamic veiling in Tunisia, showing an ankle in Victorian England, or that weird rubber bikini Miley Cyrus wore on stage at the Video Music Awards, are effectively over the same thing. Calls for women to “cover up” function to obscure women’s visibility as sexual beings. They also feed the impression that women—and their sexuality—are precious and rare.

Promoting scarcity might not be the stated rationale for these customs, but it certainly comprises one of their major effects. Feminist scholarship has long highlighted the subtle shades by which many women are rendered culturally invisible, or at least invisible as sexual beings. When commentators talk about older women, pregnant women, and mothers as if they should be uninterested in sex, they further the impression of male abundance and female scarcity.

Popular entertainment also plays a part. According to the Geena Davis Institute on Gender in Media, women land fewer than one in four speaking roles in Hollywood films. Men enjoy dramatically more screen time and lines of dialogue than women. At the same time as conjuring impressions of women’s scarcity, films often also stoke impressions of rampant male demand, particularly when so many stories paint “getting the girl” as the ultimate destination of a masculine hero’s journey.

What tale could better encapsulate romantic success in a high-priced world than a wedding between film stars, or between royals? Perhaps if a famous film-star gave up her flourishing career to marry a wealthy royal, as actress Grace Kelly did when she married Prince Rainier III of Monaco? Every time European royals, or Hollywood superstars, or even one of each, traipses down the aisle, they re-enact the fairytale of finding romance in a high-priced world. Their stories also bolster the idea that sex has high exchange value in a way that would pique the envy of De Beers and N.W. Ayer.

The oldest polarization

If a woman’s sexuality is like a diamond, a society’s social conservatives often play the role of De Beers, restricting supply and stoking demand in order to drive up the price. Witness conservative fondness for high marriage rates and frantic male striving, coupled with antipathy for teen pregnancy, scantily-clad pop stars, and “breadwinner moms.” Ideas like “true love waits” (for marriage), that married sex is (somehow) the best kind, and that a child’s “legitimacy” depends on their parent’s marital status, all bolster the impression that sex, romance, and wedded matrimony are one and the same thing. This package sells an extreme high-price, transactional deal, in which couples at the altar literally exchange all that they are and may yet become. Sealing betrothal with a diamond ring and celebrating the nuptials with an ostentatious reception tie that package up with an emphatic bow.

Why do many conservatives like a high price of sex? It suits men whose wealth gives them an edge over poorer men in the competition for mates. Wealthy parents of sons, too, benefit—in terms of evolutionary fitness—if those sons enjoy the best mating prospects and the status that comes with “marrying well.” And women who have—or have realistic expectations of—marrying upward in status and wealth also have a stake in keeping the price of sex high. People in these positions will be more likely than chance to be drawn to socially-conservative positions.

Viewed in relation to the price of sex, other ideological stoushes take on new hues. The uncivil war over abortion in the USA, for example, has everything to do with punishing unwed, young, and often poor women when they wield one of their few sources of power. The multi-front battle over Internet neutrality is about banishing pornography and sex work of all kinds, confining sex to the life-long high-price transaction of matrimony.

Social progressives argue that sexual suppression—from restricting access to divorce through to sexual double standards—harms many women and children, and some men. They argue that easing suppression delivers, on balance, more good than ill. The gains of the sexual revolution, made on the back of workplace and political change, safe contraception, legal abortion, and, yes, even freer access to pornography, represent the fastest and most dramatic emancipation of any group in humanity’s history.

Those rapid changes have inevitable downsides, including demographic and cultural upheaval, and challenges to familiar ways of living. In the last half-century, marriage rates declined and divorce rates climbed, at a cost for many individuals and families. This kind of progress can also undermine a historically-important source of women’s power to provide for themselves and achieve social mobility. As a result, progressives, particularly feminists, can find themselves conflicted about the changes that come as the price of sex drops.

Yet many changes are easy to defend. Societies that find their way to more relaxed attitudes about sex have seen same-sex couples claim a right to marry, with considerable net upsides. Sex work is safest, for both worker and client, in places that treat it as dignified work and value the economic contributions of the workers. As sexual suppression has eased, many people find, to their relief, that they can express their gender more fully and authentically than ever. Those changes happened, and continue to happen, because of a confluence of social, demographic, and technological developments, each of which contributed to a falling price of sex.

In educated, democratic, rich countries, sex is now cheaper, and less shackled to heterosexuality, property ownership, or life-long commitment, than it has been for centuries. This comes with a mature recognition that love and relationships don’t need to last forever to be worthwhile. A diamond is not forever, and neither is any given love or marriage. Much as we still might relish the high-price spectacle of a grand wedding and a multi-carat diamond, the real cost of sex has fallen for decades. Indeed economic analyses show that the trend set by Charles and Diana, Elizabeth Taylor and Richard Burton, and the entire extended Kardashian clan extends throughout Western society: the bigger the diamond, the shorter the marriage.

SexEvolutionary BiologyEvolutionary Psychologyeconomics

Rob Brooks

Rob Brooks is the Scientia Professor of Evolution at UNSW in Sydney and the author of Artificial Intimacy: Virtual Friends, Digital Lovers and Algorithmic Matchmakers