The diamond engagement ring isn’t “trad” by any means–while rings are ancient, the custom of giving one’s beloved a diamond was invented by the DeBeers corporation a mere 80 years ago.

Indeed, the entire modern wedding is mostly a marketing gimmick–I guarantee your dirt poor farming ancestors in the 1800s didn’t spring for a bachelor party (and shotgun marriages were more common than Camelot weddings)–but an insightful Twitter commentator whose name I have regretfully forgotten brings up an intriguing possibility: have diamond rings become so popular because they are an effective, hard to fake signal of future marital fidelity, thus taking the place of a traditional piece of legislation, the “breach of promise to marry“:

A breach of promise to marry, or simply, “breach of a promise,” occurs when a person promises to marry another, and then backs out of their agreement. In about half of all U.S. states, a promise to marry is considered to be legally enforceable, so long as the promise or agreement fulfills all the basic requirements of a valid contract.

According to this theory, as legal enforcement of punishments for breaking marriage contracts fell by the wayside, people found new ways to insure their relationships: by spending a huge hunk of cash on a non-refundable diamond.

This is a really nice theory. It just has one problem: the amount of money spent on a diamond is a really poor predictor of marital quality. In fact, researchers have found the opposite:

In this paper, we estimate the relationship between wedding spending (including spending on engagement rings and wedding ceremonies) and the duration of marriages. To do so, we carried out an online survey of over 3,000 ever married persons residing in the United States. Overall, we find little evidence that expensive weddings and the duration of marriages are positively related. On the contrary, in multivariate analysis, we find evidence that relatively high spending on the engagement ring is inversely associated with marriage duration among male respondents. Relatively high spending on the wedding is inversely associated with marriage duration among female respondents, and relatively low spending on the wedding is positively associated with duration among male and female respondents.

People who spend more on diamonds (and weddings) get divorced faster, but it appears there is a sweet spot for rings between $500 and $2000. Not having a ring at all might spell trouble, for going below $500 also increases your chance of divorce–but not nearly as much as spending over $2000.

The sweet spot for the overall wedding is… below $1000. This is a little concerning when you consider that, according to PBS, the average couple spends about $30,000 on their wedding.

These finding may have an immediate cause: debt is bad for marriage, and blowing $30,000 on a wedding is not a good way to kick off your life together. There may also be a more fundamental cause: people who are impulsive and bad at financial planning may also be bad at managing other parts of their lives and generally make bad spouses.

There is one bright spot in this study:

Additionally, we find that having high wedding attendance and having a

honeymoon (regardless of how much it cost) are generally positively associated with marriage duration.

This is probably because these are activities you do with people you actually like, and the sorts of people who have lots of relationships and like doing things with their friends are good at relationships.

So skip the wedding and just invite all of your friends to a big party in Tahiti.

(If you’re wondering, we spent about $1500 on our wedding and I hand made the rings, and we are now the most successfully and longest-married couple in my entire extended family.)

How did we all get bamboozled? The process by which diamond rings became the engagement staple is really something:

The concept of an engagement ring had existed since medieval times, but it had never been widely adopted. And before World War II, only 10% of engagement rings contained diamonds. … Creating the Narrative: The agency wanted to make it look like diamonds were everywhere, and they started by using celebrities in the media. “The big ones sell the little ones,” said Dorothy Dignam, a publicist for De Beers at N.W. Ayer. N.W. Ayer’s publicists wrote newspaper columns and magazine stories about celebrity proposals with diamond rings and the type, size, and worth of their diamonds. Fashion designers talked about the new diamond trend on radio shows. N.W. Ayer used traditional marketing tools like newspapers and radio in the first half of the twentieth century in a way that kind of reminds me of inbound marketing today: In addition to overt advertisements, they created entertaining and educational content — ideas, stories, fashion, and trends that supported their brand and product, but wasn’t explicitly about it. According to The Atlantic, N.W. Ayer wrote: “There was no direct sale to be made. There was no brand name to be impressed on the public mind. There was simply an idea — the eternal emotional value surrounding the diamond.” Their story was about the people who gave diamonds or were given diamonds, and how happy and loved those diamonds made them feel.

People didn’t realize this was marketing. It just felt like “culture,” and to those who grew up with media saturated with “diamonds=love,” it already felt “traditional” by the time they were ready to marry.

Remember this–there’s a lot more “marketing” going on than just the explicit ads on TV.