The result? A chalky, cloudy Gimlet that tasted of Disprin. Pearls have long had a reputation as an aphrodisiac—pearl preparations promising Viagra-like results are still widely available today. (Pliny does not record what happened after Cleopatra won her bet with Antony.) I noticed no side effects of that kind, or none that I would not have attributed to the gin alone. But I was buoyed by the notion that the high calcium-carbonate content of the pearl put the cocktail on a par, nutritionally, with a glass of milk.

Anecdotes like Pliny’s are an important part of what makes gems attractive. In this respect pearls are no different from emeralds or rubies or any commodity that has been transformed through the power of storytelling from mere stuff into the stuff of legend. Yet in certain respects pearls are indeed very different. They are the only gem produced by a living animal. They require no cutting or polishing. They are unique in their ancient and near-universal appeal—no other gem has been so widely prized for so long. The oldest surviving pearl necklace, held in the Louvre, was recovered by archaeologists in Persia and dates from the fourth century b.c. Effective techniques for faceting gemstones, by contrast, were only intro-duced in the middle of the 17th century.

But what really sets pearls apart from other gems is the particularly vivid way in which they highlight our tendency to destroy the things we love.

II

From antiquity until the 1970s the principal commercially pearled oyster beds lay in the Persian Gulf, the Red Sea and the Gulf of Mannar, between India and Sri Lanka. Conditions were often harsh. For divers, internal bleeding, blackouts and the bends were everyday hazards. Crews in the Persian Gulf would stay at sea for months at a time, but even the innocent distraction of singing was not without an element of danger. Superstition held that certain melodies favoured by pearlers would lead to blindness if sung aloud.

According to one 19th-century visitor to Sri Lanka (then Ceylon), the pearl-harvesting season began with incantations “to render the terrible sharks and other monsters of the deep harmless”. Weighted with stones, divers plunged to the oyster beds until their ears began to ring and they were yanked back up to the surface by ropes attached to their legs. Mounds of oysters grew on the beach “till their fleshy contents had rotted away” and their pearls were exposed—the stink was horrendous. The pearls were then sorted by size through a series of brass sieves. “The finest would be immediately secured for the Indian Courts, and the inferior kinds as well as the seed pearls transported to Europe to be used in the aljofar work of the Moors, which bedecked the Court dresses of the Iberian beauties.”

It was an Iberian beauty, Queen Isabella of Spain, and her husband King Ferdinand who sponsored Christopher Columbus in his risky “enterprise of the Indies” to find a shortcut to the riches of the East. Before he set off on his first voyage in 1492, a deal was struck. Columbus would gain authority over the lands he discovered, plus ten percent of the profits. At the top of the monarchs’ wish-list were pearls.

These, however, were harder to come by than they or Columbus had hoped. It was not until his third voyage, in 1498, that he had any luck. By the mouth of the Orinoco River, in what is now Venezuela, Columbus bartered for pearls with needles, scissors, buttons and broken plates. Enquiring about the source of the pearls, he was directed to what would soon become known as the Pearl Coast, the richest pearling grounds in the Americas. But in a baffling lapse of judgement, Columbus failed to inform Isabella and Ferdinand of his discovery. When they got wind of it, they were furious, and in 1500 he was returned to Spain in shackles.