Anna was telling me about the clever Tiffany’s campaign, which singlehandedly spread the idea that the right amount to spend on a diamond engagement ring was three month’s of the man’s income.

‘They even put a calculator on their website so that the man could work out how much he should spend,’ she said. ‘Although, any man who needs that calculator probably isn’t worth it…’

‘I read somewhere that the original reason for the diamond engagement ring was because once people got engaged, well, it was kind of like they could start sleeping together,’ I said.

Anna looked puzzled. ‘Was it to prove that they really were engaged?’

‘No. It was in case the woman got pregnant and then got dumped. She would at least still get some money to survive on by selling the ring.’

Anna considered this briefly. ‘So the ring’s like a deposit?’

I started laughing. ‘Exactly!’