If we had any spare money – on two junior journalist wages – it would all go straight into the joint bank account for The House, not on some gaudy trinket neither of us needed.

Well before we were ever advised to put a ring on it if we liked it, I was pretty confident that if I was going to wear any wedding jewellery, so was my beloved. It always seemed strange to me that only women wore engagement rings. We did, in the end, buy two wedding rings, made by a woman whose name I recall as Julie Goldthorp. We decided on two 18 carat gold bands, slightly wavy, to signify the ups and downs of married life. This is prescience, people.

I recall this only because of the story of Edwin Shien Bing Toh who demanded his former fiancée Winnie Chu Ling Su return the $15,500 diamond engagement ring he gave her when the pair decided to marry and the wedding bands they bought together. A few months later – and only 10 days before the wedding was scheduled – it was all over, red rover.

The magistrate Rodney Brender, who heard the case, ordered the return of the wedding bands but not of the engagement ring because "the gift of an engagement ring should be seen as unconditional".

That's news to me. I always thought engagement rings were a sign that a wedding was in the offing. It's a shame neither Su nor Toh – as they lavished gifts on each other – read groundbreaking US research that has scarcely made a significant material impact since it was published two years ago.

Seriously. The most useful economic research ever to emerge hasn't changed the way we think about spending on marriage. And it should.

When Andrew Francis-Tan and Hugo Mialon revealed that the more a couple spent on their engagement rings and wedding preparation, the more likely their marriage was doomed, actually doomed (OK, not actually doomed but less likely to last), you would have imagined that participants in this strange ritual called marriage would say to themselves, hold up, do we actually need to spend three months salary on a ring.

Francis-Tan and Mialon explained that the wedding industry tries to link wedding spending with long-lasting marriages.

As they wrote at the time, industry advertising has fuelled the idea spending large amounts of money on a wedding is a signal of commitment or is helpful for a marriage to be successful.

These two economists, who ought to be awarded the Nobel Prize for Economics, set out to investigate whether there really was a link between long-lasting love and money.

The answer is no. Not in any way. What they discovered was that "marriage duration is either not associated or inversely associated with spending on the engagement ring and wedding ceremony ... overall, our findings provide little evidence to support the validity of the wedding industry's message connecting expensive weddings with positive marital outcomes."

Not associated or inversely associated. Here's the truth. Those researchers did an excellent job of quantifying the relationship between love and money. One doesn't beget the other.

As for engagement rings, they are never ever a good investment. You can't return them. It's hard to sell them second-hand for even half of what you paid for them. And you can't wear them unless you stay married to the person with whom you bought the ring.

A spokesperson for the Australian Competition and Consumer Commission says consumers are protected if the product is faulty but not for "change of mind". Quite. That's up to the retailer and why would you take back a ring with bad karma?

I called George Bezos, from Bijoux in Canberra. He's pretty clear on the rules around engagement rings. On the whole, he doesn't do refunds.

"Every case is different and every client is different ... we don't give refunds but sometimes we give them credit in the store," he said.

Plus, if it's handmade specifically for the client, there is no recourse at all. What would you do with someone else's taste?

He says the majority of their engagement rings fall into the $10,000 to $15,000 band – and the older we get, the more likely we are to spend more.

He's also had clients come back after a futile first attempt to buy another ring.

"Plenty of times ... even after a failed marriage people come back. They say: 'I like your work.'"

Michael Hill Jewellers do take back engagement rings within 30 days - so long as they haven't been worn - and that's at its discretion.

Don't imagine Toh and Su are unusual. Court cases about engagement rings and other wedding gifts abound and reading the transcripts makes you realise that no expense is spared when making the life of a former fiancé/e utterly miserable. There's a war out there.

If you think love is based on how much money you spend on each other, your relationship is headed for the rocks. And not ones you can measure in carats.

Jenna Price is an academic at the University of Technology Sydney

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