Although De Beers has been trying to convince us that "diamonds are forever" since 1947 when copy writer Frances Gerety coined the iconic slogan, the gemstones' popularity traces back around 600 years. Up until the mid-1400s, diamonds not only were rare, coming exclusively from India, but cut diamonds also were often sanctioned only for kings and religious iconography. Some royal edicts even forbade non-royals, especially women, from wearing them. But by the mid-1400s, wealthy women would accessorize with diamond jewelry, a trend commonly attributed to Agnes Sorel, mistress of French King Charles VII (see: Joan of Arc) who was also known as Dame de Beauté, or Lady of Beauty.
Sorel's position as a publicly acknowledged mistress to the king likely had a much larger historical impact than her taste in jewelry. As the French royalty's first "official" mistress, Sorel aroused scandal and jealously among courtiers who looked askance at Charles' outpouring of wealth, real estate and, of course, diamonds. Historical legend maintains that Sorel intentionally wore a diamond necklace (supposedly the first recorded diamond necklace in history) to court, and the baubles subsequently caught Charles' eye. Once Charles and Sorel became involved, the king employed the service of a jeweler to fashion custom pieces for the comely, high-profile courtesan. Not too long afterward, in 1477, Archduke Maximilian of Austria gave Mary of Burgundy history's first known diamond engagement ring.
Until the late 19th century with the discovery of a massive diamond mine in South Africa, diamonds remained available only to the extremely wealthy and royal. And in the 20th century, it took a decades-long marketing initiative orchestrated by De Beers to put diamonds on the left hands of 75 percent of American brides. In which case, a more accurate -- though more challenging to fit on a billboard -- ad slogan would be "diamonds are since the 15th century, but only if you were really, really rich or a royal mistress."