Every gemstone is a mineral. Except the pearl.

Diamond is carbon crystallised under pressure. Ruby is corundum with chromium. Jadeite is an aggregate of sodium aluminium pyroxene. All of them form in the earth’s crust, in places without life, across geological time. The pearl is different. A pearl is a mollusc’s response to an intruder — a product of the immune system, something made by a living creature while it is still alive.

The intruder can be a grain of sand, a parasite, any foreign body that enters the mollusc and cannot be expelled. The mollusc coats it in nacre. Nacre is a composite of calcium carbonate and organic proteins, secreted in layers, each layer extremely thin — thin enough for light to pass through, to refract between layers, to produce the effect of luminosity from within. The trade calls this lustre; in English, orient. It is not ordinary reflection. It is interference between layers of light.

The mollusc secretes nacre slowly. South Sea pearl cultivation typically takes two to four years, and that is already an accelerated result of human intervention. Wild pearls take longer, and form rarely. Before the nineteenth century, pearls were among the most expensive objects in the world — more expensive than diamonds — because they depended entirely on chance. Divers went down, opened hundreds of molluscs, and might find nothing.

South Sea pearl production is concentrated along an arc: from the northwest coast of Australia, through Indonesia, to the Philippines. This arc corresponds to the range of the silver-lipped pearl oyster, Pinctada maxima — the largest of the pearl oysters, producing the largest pearls, typically ten millimetres or more in diameter, occasionally exceeding twenty.

The main cultivation areas in the Philippines are in the Sulu Sea, near Palawan. The water temperature is stable, plankton is abundant, visibility is high — ideal conditions for Pinctada maxima. Farms suspend the oysters at depths of a few to fifteen metres, inspect them regularly, remove algae and parasites from the shells, manage stocking density to prevent water quality from deteriorating. Each oyster is managed individually, because disease in one can spread to those around it.

Nucleation is the critical step. A technician makes a small incision in the oyster’s mantle with a scalpel, inserts a round nucleus ground from freshwater mussel shell, and implants a small piece of mantle tissue to serve as the source of nacre-secreting cells. The procedure must be completed within a few minutes. The oyster’s survival rate and the quality of the pearl it produces both depend on the precision of this operation. After nucleation, the oyster goes back into the sea and begins the next two to four years of work.

A round pearl is the result of nacre coating the nucleus evenly. The nucleus is spherical; nacre is secreted at the same rate in every direction; the result is a sphere. This requires the oyster to maintain a stable position throughout its growth cycle, nacre secretion to remain consistent, and no disruption of any kind.

This condition is difficult to sustain.

Oysters move in the water, are buffered by currents, fall ill, secrete nacre faster in some seasons and slower in others. Any unevenness is recorded in the shape of the pearl. A baroque pearl is the record of that unevenness — nacre accumulating more in one direction than another, the shape shifting, swelling, dipping, forming a protrusion or a curved plane. Every baroque pearl is unique because every oyster’s growth history is different.

The value of a round pearl lies in its perfection and consistency. The value of a baroque pearl lies in the fact that no two are alike. Two aesthetics, two logics. Both have their adherents.