Kamala D. Harris’s pearls seem like fuel cells, powering her from countless campaign stops to media appearances to committee hearings. She wore pearls when she was sworn into the Senate, and as far back as her graduation from Howard University in 1986. These small globes of light communicate many historical messages: purity and innocence, yes, but also wisdom, ambition and incorruptibility.

But Harris’s black pearls say the most. She wore them when she kicked off her presidential campaign in January 2019, at the presidential debate in Detroit, then back on the campaign trail with Joe Biden the next year. She wore them at her first speech on the Senate floor in February 2017 and the following December to call for the passage of the Dream Act; honoring Justice Ruth Bader Ginsburg as the first woman to lie in state in the Capitol; and keeping it real with kindergartners at signings for her book “Superheroes Are Everywhere.” Most recently, it was during a CNN interview that Harris and Biden gave Thursday. Her black pearls, indeed, are everywhere.

We speak through our dress, and in these key moments, Harris’s choice conveys toughness and barriers demolished. Harder than white pearls, black pearls signal the “fighting spirit” the vice president-elect credits to her mother. The history of how they won esteem despite centuries of bias favoring white pearls is a trajectory shared by women — especially those of color — who aspire to high political office. Iconoclasts who smash stereotypes and glass ceilings wear black pearls for a reason.

Throughout most of human history, black pearls were as absent as the female vote. White pearls, fished from the Persian Gulf, the Indian Ocean and later from the Caribbean, were the desirable norm for jewelry and adornments. From European royalty to Mughal emperors to Holly Golightly with a pastry outside Tiffany’s, wearing white pearls conveyed status and the status quo. But in warm lagoons in the southern Pacific Ocean, 1 in 15,000 black-lipped oysters grew a black pearl.

Spanish and Portuguese navigators visited the islands that are now French Polynesia in the 16th century. The British claimed Tahiti in 1767, the French a year later. Europeans questing for tropical commodities and missionaries questing for souls noticed islanders wearing the curious black gems. There was little overseas demand for the baubles until Tahiti became a French protectorate in 1843, and black pearls reached French markets. Rarer than white pearls, they caught the fancy of Empress Eugénie, and an exclusive trend was born. They were the photo negatives of white pearls — chic, mysterious and exotic, just like the native people on these islands in the French imagination.

European entrepreneurs soon harvested the Pinctada margaritifera, the black-lipped oyster, not just for its occasional pearls but for “mother-of-pearl,” the material that lined the inner shell. Shipped out by the ton, the shell was used for buttons and inlays. Proceeds from pearling lined the colonial administration’s coffers and European traders’ pockets, but the Polynesian islanders weren’t getting rich. Divers were caught in a vicious cycle of servitude, as merchants extended them credit and then paid a pittance for their haul. Overfishing put pressure on the aquatic environment and indigenous people, and at the end of the 19th century the trade collapsed.

In response to the oyster beds’ depletion, the French government encouraged experiments with oyster farming and pearl culturing — and they weren’t the only ones. A pearl is an accident of nature — the mollusk’s biological response to an intruder such as a tiny parasite. Depending on species and environmental conditions, they might grow in 1 in 100 or one in several thousand animals. For this reason natural pearls will always be scarce, and the prices for gem-quality pearls eye-wateringly high. Culturing, successfully pioneered in Japan in the early 20th century, solved the problem, allowing less expensive white pearls to satisfy the growing demand in department stores by middle-class buyers.

But when French entrepreneurs cultured black pearls on farms in French Polynesia, they struggled to find buyers. People were suspicious of their origins and their color's complexity, which shimmered between black, silver and sea green. No jeweler would promote them. The middle class could afford pearls because of new technology, but their tastes were shaped by entrenched associations between white and purity, cleanliness and perfection.

This changed when marketing wizardry put the emphasis firmly back on the myth of unsullied Polynesian nature. Pearl authority Elizabeth Strack tells of the trade's Italian-born godfather, Salvador Assael, offering cultured black pearls in 1973 to New York’s most blue-blooded jeweler, Harry Winston. Initially reluctant, Winston bought 18 strands. Assael, who had his own stake in Polynesian pearl farming, wove the artful seduction that black pearls were from Tahiti's turquoise waters. In fact, they were farmed in remote lagoons, but Tahiti was a tourist haven, and “French Polynesia” had a tropical charm.

Van Cleef & Arpels, Cartier, and Tiffany picked up the scent, and soon New York fashionistas were paying hundreds of thousands of dollars for the latest must-have dark gem. These were, of course, cultured black pearls. But displayed in the Fifth Avenue windows of celebrity jewelers, they were presented as the almost priceless results of a partnership with nature. Advertisements announced, “A New Gem is Born.”

Convincing a skeptical public that these dark orbs were as desirable as white ones was a marketing triumph. They were adopted by luminaries such as Isabella Rossellini and Elizabeth Taylor, who in 1996 launched a Black Pearls perfume: “rare, sought after, coveted, from a world apart.” This was certainly true of the pearls. In the mid-1980s, the best-quality black pearls were double the price of the most expensive white ones. By the end of the millennium, annual production was worth $170 million. Prices dropped sharply when supply outstripped demand, but fine quality black pearls are still pricey.

Appealing to novelty and exoticism ignited the trend for black pearls, but they later became a proud statement of difference. Black pearls, described by journalist Stephen G. Bloom as “the renegade pearl, the 180-degree pearl, the opposite of the stereotypical society jewel,” will always be ‘other’ to white pearls. They claim their space, just like their wearers. When trailblazing women of color such as Harris, Michelle Obama or Susan E. Rice wear black pearls, their jewelry is not just fashion but an embodiment of pearls’ history. Black pearls point to disruption, prejudices undone and the respect we owe to the natural world.

Where white pearls say, “I’m listening,” black pearls say, “I’m speaking.”