Pearls have been considered glamorous for a long time: they were famously worn by Julia Child, and Audrey Hepburn’s most iconic picture involves a giant pearl necklace. Romans even had specialized doctors to treat earlobes that became infected or injured by supporting ornaments laden with pearls, ‘respectability’, and in some cases, tumors.
Natural pearls are extracted from oysters, a form of bivalves. Diving for pearls and capturing the unsuspecting oyster used to be the predominant industry in some regions, such as the Persian Gulf. However, not every oyster houses a pearl. This is because pearls first begin as a useful layer to protect an oyster; the formation results from a biological process, which starts when an oyster encounters a foreign particle.
The inner layer of a two-part shell of an oyster (kept open by a ligament so that the oyster can eat) is made from a substance called nacre. This material is produced by a vital organ called the mantle. If a foreign particle manages to enter the oyster, it can irritate¬ the mantle; this is the beginning of a natural pearl. The oyster reacts, and its man¬tle covers the foreign substance with coatings of nacre, which ultimately shapes into a pearl.
A pearl is then an obtrusive, foreign particle coated with several layers of nacre, or mother-of-pearl, which is responsible for its luster. Often, pearls have an irregular shape and are known as baroque pearls. But it is the perfectly rounded pearls that are the most valued. There is a claim that it acquires a round shape because of a turning movement, resulting in an even deposition of nacre on its surface. The surface of a pearl has been examined under a scanning electron microscope, and a saw-tooth texture has been observed that perhaps helps the pearl to rotate as it develops, resulting in the prized sphere.
So not all pearls are round and not all oysters have pearls. In the earlier days, they were not manufactured artificially either, and the natural pearls were not cut, faceted or polished. These organic jewels were also delicate to handle because their soft structures are not protected once extracted from the oyster. Nicely rounded pearls were therefore rare, and pearls in general, were quite expensive. They also had a human price; the pearl divers had to endure many hardships, spend months at sea surrounded by hostile sea creatures with no fresh water to rinse their malnourished bodies. They suffered from frequent, often fatal, illnesses. During colonial times, many of them were treated inhumanely, several died, and the ones that survived had to accept low wages.
Now, of course, we have mastered the art of tricking oysters. Pearl harvesters are able to produce cultured pearls by opening the shell of an oyster, creating a small slit in the mantle tissue, and introducing irritants that nucleate into lustrous pearls. Manufacturing them has crippled their value because they are no longer rare. However, overharvesting has caused a severe decline in oyster beds.
Formation of pearls is an interesting phenomenon, physically and biologically, because some of these organic items display dazzling spherical symmetry. And yet, chemically, pearls take on an unarresting personality of aragonite calcium carbonate, water, and an organic binding material. These simple ingredients combine when an oyster starts to feel uneasy due to a foreign object inside its shell. And this is the key: the oyster has to be annoyed else you will only get a hollow shell. Perhaps the Shakespearen phrase should be reworded to ‘the world is your inconvenienced oyster’.