A pearl is a gem grown by a living animal. When an irritant settles inside a mussel or oyster the animal wraps it in nacre — the same material it uses to line its shell. Those nacre layers stack up over time, and that build-up is the pearl. Nacre is mostly aragonite, a form of calcium carbonate, laid down in microscopic platelets; the way light bends through those platelets is what gives a good pearl its depth and glow.

A strand of Australian South Sea pearls up to about 15 mm can sometimes be matched from a single harvest. Exceptional strands take three harvests or more, and some have taken far longer. The honest answer is that it is not simple: large pearls of close colour, luster and shape are scarce, so we hold back fine pearls year after year to have enough to match. It is entirely possible for one pearl in a strand to come from a 2004 harvest and the next from 1994.

The farms run along more than 2,500 kilometres of coastline — from the Cobourg Peninsula to Exmouth on Australia's north-west coast. That is roughly the distance from London to Moscow. It is also the heart of the northern cyclone belt, which faces some of the fiercest tropical storms anywhere, so keeping the operation running and the workers who tend the oysters daily safe is a year-round management task in itself.

Kuri Bay traces back to the post-war revival of the pearl coast. This remote settlement was founded in 1956 as Australia's — and the world's — first South Sea pearl farm. It was named for Tokuichi Kuribayashi of Nippo Pearl, the company that supplied the technical know-how for that early joint venture.

In rough order of weight on price: Lustre, Complexion (surface), Shape, Size, Colour. Luster comes first because no amount of size or colour rescues a dull pearl — it is the one thing you cannot fake or improve after the fact.

Roughly 3 to 4 years old before the first operation.

Annually from May to September.

It depends on the size and health of the oyster, so there is no single figure. What matters far more is the nacre thickness that grows over the bead. Akoya pearls (Pinctada fucata) carry a nacre coat of only around 0.1 mm; on a 13 mm Australian South Sea pearl the average is 2 to 4 mm — which is why South Sea nacre reads so much deeper and more durable.

The best nucleus is cut from 100 per cent hand-selected Mississippi clam shell. Decades of practice point to the same conclusion: this freshwater shell shares almost the same specific gravity and composition as the nacre of the Australian South Sea pearl, so the bead and the new nacre move and age together, giving a durable result. Lower-grade beads, including plastic, turn up in some cheaper Chinese freshwater production and do not behave the same way.

Around 800 people work across the pearl production divisions of the business.

Each oyster is cleaned by hand at least once a month — more often in the Dry season and less in the Wet. Fouling organisms compete with the oyster for food and oxygen, so this hand-cleaning is one of the unglamorous reasons South Sea nacre stays so clean.

Usually once. Occasionally twice, and only rarely a third time. Each successful operation lets the oyster grow a larger pearl around a larger bead, which is part of how the biggest South Sea pearls are produced.

Australian South Sea pearls grow over 2 to 3 years. Other South Sea pearls take 1 to 2 years, and Akoya only about 6 months on average — the short Akoya cycle is exactly why its nacre stays thin.

Bigger than a dinner plate, at roughly 50 years of age. The pearl oyster used here is Pinctada maxima, the largest pearl-producing mollusc — which is the whole reason South Sea pearls reach the sizes they do.

Durability is not uniform across all pearls; untreated pearls hold up far better than treated ones (treatments include dyeing, bleaching and chemically boosting lustre). Australian South Sea pearls are valued precisely because their colour is natural and untreated.
Akoya pearls are generally the most fragile cultured pearls because of their thin nacre; an Akoya is rated good quality at just 0.15 mm of nacre, and Akoya are almost always treated in some way. Good Australian South Sea pearls carry at least 2 mm of nacre on average. That thick, natural nacre responds well to skin oils, but being calcium carbonate it is softer than diamond and will etch on contact with acids — the same chemistry that attacks tooth enamel — so keep them clear of vinegar, citrus and harsh cleaners.

The global jewellery market is dominated by gold, silver and diamonds; pearls account for only about 2 per cent of total jewellery value. Within cultured pearls, Australian South Sea make up roughly 1 per cent of world production by volume yet close to a third by value. That gap reflects a clear preference for quality, and it keeps fine pearls scarce: production cannot be ramped quickly, because lead times run into years and you cannot shortcut a living oyster.

Natural Australian South Sea pearls are rarely found in the wild today, but a well-grown cultured pearl is virtually indistinguishable from those natural ancestors — both are real nacre laid down by the same species.

Nature decides shape and colour, not the farmer. The implanted nucleus or seed goes in round, but because South Sea oysters lay down such thick nacre, the pearls emerge in a wide range of shapes — round, near-round, drop, button, oval, circlé and baroque. Perfect symmetry is uncommon in nature, so round commands the highest prices. See The Five Virtues for how Australian South Sea pearl shapes are described.

Also called a mabe or cultured blister, the half-pearl starts with a hemispherical nucleus glued to the inside of the shell. As the oyster secretes nacre over it, a domed blister forms; it is later cut from the shell and backed with mother-of-pearl. Because only one side is finished nacre, mabe sit flush against a setting and work especially well in earrings and rings.

'Keshi' is Japanese for 'small'. Keshi can be natural or cultured, with a solid nucleus (such as a grain of sand), a soft nucleus (a small piece of organic material), or a hollow centre — but never an implanted bead. Since they cannot be told apart by eye, all keshi are classified as cultured unless x-ray and a certificate from a reputable gemmological laboratory prove otherwise. They usually run 2 to 10 mm and stay quite rare, which is why fine keshi are prized for their solid all-nacre body and unusually high luster.

The colour of South Sea cultured pearls is set by nature alone and mirrors the mother-of-pearl of the oyster that grew it — never a dye. The finest Australian Pinctada maxima oysters carry bodycolours from white and silver through to deep gold, and the pearls follow suit. Many also show coloured overtones that, combined with translucent lustre, produce the play of colour known as orient. Note that peacock, aubergine and true black belong to Tahitian pearls from Pinctada margaritifera, not to white or golden South Sea pearls.

A South Sea pearl is grown by Pinctada maxima, the largest pearl-producing mollusc. They come mainly from Australia, largely with wild oysters, and from Indonesia and the Philippines with hatchery-reared oysters. The species runs in two colour lines — the silver-lipped oyster gives white and silver pearls, the gold-lipped gives the famous golden tones.