And even the ones who didn’t consciously adhere to the rule ended up spending that much anyway, suggesting two months’ salary is a figure we arrive at naturally: When you’re ready to marry, one-sixth of your yearly income just feels like the right amount to spend on a ring.
How the Diamond Industry Scammed Us Into Spending Two Months’ Salary on an Engagement Ring
John McDermott

Yes but. Given the thrust of your excellent article, John, it may feel “natural” to fork over two months’ salary today only because the mass cultural mesmerism of the De Beers advertising machine first implanted that suggestion four decades ago. Boom!

Consumerism feeds off a sense of lack, which savvy marketers beginning with J. Walter Thompson in the late 19th century learned how to induce in the US populace in order to manipulate it. (It’s how Clairol’s “Do blondes have more fun?” and Blackglama(r)’s “What becomes a legend most?” got the power.) These days the virus is happily breeding in the DNA of millennials.