Explanation: The De Beers mining company has controlled a large share of the world diamond market for ~150 years now, and has leveraged that share of the diamond supply to convince the world that they're ultra-rare and valuable, far beyond other gemstones. In the 1950s, they doubled down on this scam, launching a marketing campaign to establish diamonds as the new 'norm' for engagement rings and the like.

The Millennial generation born in the 80s and 90s have had less interest in diamond rings than previous generations, like so many other industries, we are blamed for the decline of a fad.

[laughs maliciously in Millennial]