Diamonds have been mined for hundreds of years, but their ideology as a symbol of wealth and esteem is a fairly recent innovation.

Until the late nineteenth century, diamond production was limited to a few hundred pounds per year, with most of the stones being excavated from riverbeds in India and Brazil. Things changed in 1870, when huge diamond mines were found in South Africa, and the gemstones were being scooped out by the ton. Suddenly those financiers who’d invested in diamonds feared that the new abundance of stones would result in their investment being reduced to “semi-precious gem” status. The major diamond players decided to merge into one entity that would be powerful enough to control the world’s diamond supply. The result was the De Beers Consolidated Mines, Ltd., which quickly embarked on a marketing plan that would eventually control demand as well as supply.

Prior to 1938, engagement rings more often than not were comprised of a combination of the bride and her mother’s birthstones, which meant that sapphires, rubies, and emeralds were the order of the day. But in 1938, Harry Oppenheimer, the son of the DeBeers founder, approached a Madison Avenue advertising agency with the task of making diamonds appealing to a Depression-era America. The firm came up with the “a diamond is forever” campaign and managed to convince young American men that the only way to express true love and commitment was to present their girl with a diamond ring. Additionally, the “forever” part of the slogan encouraged buyers to hold on to their diamonds as heirlooms, and not release them back into the market.

The promotion worked. “Diamonds are a girl’s best friend” entered the realm of pop culture, as did Elizabeth Taylor and her impossibly huge diamond rings. It is estimated today that 78 percent of the engagement rings sold include at least one diamond.