The Wide World of Pearls, Our 115th Issue: How Are Pearls Cultured?

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Every day we receive questions from customers all over the world about pearls. We decided to post our answers here for every one to read!

How Are Pearls Cultured?

We Answer:

Pearls are cultured through a process known as pearl farming, which involves implanting a nucleus into a mollusk and allowing it to develop over time. Here's a step-by-step overview of the process:

Selection of Mollusks: Pearl farmers typically use oysters or mussels for culturing pearls. The species most commonly used are the Akoya oyster pinctada fucata martensii, Tahitian black-lipped oyster, Pinctada margaritifera, the South Sea pearl oyster both white and gold-lipped varieties, Pinctada maxima, and Freshwater mussels hyriopsis cumingii.

Nucleation: A perfectly round, white bead nucleus along with a tiny 1.0mm square of donor mantle tissue is used for saltwater pearl oyster nucleation. The bead nucleus and mantle tissue are inserted into the gonad (reproductive organ) of a host mollusk. The bead nucleus acts as an irritant, stimulating the mollusk to produce nacre, the substance that forms the pearl. The mantle tissue is thought to influence the pearl's final color.

In the case of Freshwater pearls, only mantle tissue is used to nucleate the pearl mussel.

Read More: Freshwater vs. Saltwater Pearls

Insertion: The nucleus and mantle tissue are carefully inserted into the host mollusk. This delicate procedure requires skill and precision to ensure the health of the mollusk and the quality of the resulting pearl. The incision is carefully closed and smoothed over, and the newly nucleated oyster or mussel is allowed to recuperate from the operation.

Cultivation: The mollusks are then placed in underwater racks or baskets, suspended in water or anchored to the seabed, depending on the farming method. They are left to grow and develop the pearl over a period of time, typically ranging from several months to a few years, depending on the type of pearl being cultured. Divers swim down to check each oyster to periodically the oysters are cleaned and checked for growth or rejected nuclei as well as make sure the oysters are overall healthy and happy.

Nacre Formation: In response to the irritant, the mollusk creates a pearl sac to enclose the nucleus, and then begins secreting layers of nacre (mother-of-pearl) around the bead, gradually forming a pearl. The thickness and quality of the nacre layers determine the luster, color, and overall quality of the pearl.

Harvesting: Once the pearls have reached the desired size and quality - typically a period of time ranging from 18 months to 3 years for larger pearl sizes and types - they are carefully harvested from the mollusks. This involves opening the shells, removing the pearls, and assessing them for quality.

For South Sea and Tahitian pearl oysters, the animal is allowed to recover from the harvest, and then later re-nucleated with progressively larger bead nuclei to produce larger pearls. After a long, productive life creating pearls, these oysters are often returned to the open ocean to begin spreading its genetics to the wild oyster populations.

Sorting and Grading: The harvested pearls are sorted according to size, shape, color, luster, and surface quality. They are then graded based on these characteristics, with higher-quality pearls commanding higher prices.

Processing and Treatment: Some pearls may undergo additional processing or treatment to enhance their appearance or durability. This may include polishing, bleaching, dyeing, or irradiation, depending on the desired outcome.

Distribution: The cultured pearls are then distributed to wholesalers, retailers, or jewelry manufacturers for use in jewelry or other decorative items.