'How are pearls made' is a mystery explained in the many Polynesian legends surrounding Tahitian black pearls.
Perhaps the glory of the heavens has come to rest on the ocean floor in the iridescent mother-of-pearl. Or has imagination created fantasy from a curious act of nature, and the black-lipped oyster simply protects it's delicate flesh by coating an intrusive grain of sand with aragonite, a form of calcium carbonate. These precious pearls are so valuable that man has intervened to simulate nature and have oysters making more. And specific criteria define what may be sold as cultured Tahitian pearls.
Long ago...it is said...Ora, god of peace and fertility, came down to earth on a rainbow and gave a pearl from Te Ufi (the black-lipped oyster) to the beautiful Princess of Bora Bora to demonstrate his love for her.
It is also said...the moon bathes the ocean with it's light, to attract Te Ufi to the ocean surface, and infuse him with dew from the heavens. Time polishes this radiant drop of heavenly light and coats it with a glossy mantle of harmonious blue, green, pink and golden luster.
Tahitian black pearls became desirable commercially about 1870. At the Tuamoto lagoons, island divers (wearing only small goggles) were employed to descend to depths of 25- 30 meters to gather oysters. The main purpose was to collect shells for producing mother-of-pearl buttons. In the natural environment of Polynesian lagoons only 1 oyster out of 15,000 has a pearl. Oyster beds are slow growing, so by 1960 the oyster numbers had been depleted. Now, oysters are only gathered to supply Tahitian pearl farms.
A Frenchman, Jean-Marie Dormand arranged (with the French Polynesian Government) to bring a Japanese pearl oyster technician to Tahiti. In 1963, as an experiment, the first Tahitian pearl farm was created in the Tuamotos at Hikueru Atoll. An atoll derives rich mineral salts from the depths of the cold waters, and the coral crown develops from photosynthesis in the tropical sun. This provides an ideal environment for the black-lipped oyster. In 1965, 1000 pearls were successfully harvested.
Due to the desire for beautiful Tahitian pearl jewelry, there are now thousands of people employed in hundreds of cooperative and private Tahitian pearl farms on 26 atolls. Many Polynesians who left after destructive hurricanes in 1983 have returned to work in the Tahiti pearl industry. Some family farms still produce pearls. About 85% of the industry is controlled by Robert Wan's Tahiti Perles and several other large private companies. This is because they utilize a vertical business model for farming, wholesaling and retailing. Find out where you can visit a pearl farm and shop for Tahitian pearl jewelry while in French Polynesia.
Tahitian pearl farming has ecological benefits as it allows renewal of natural oyster stocks. It also acts as an impetus to preserve marine environments, as either sewerage, or run off from fertilizers used in agriculture would affect the oysters. But turtle survival has become an issue. Their favorite food is oysters. So wire fencing need to be coiled around the hanging strings of oysters to prevent turtles breaking open the shells and feasting on the pearl farmer's harvest. Some Tahitian Pearl farms find it easier to cull the turtles.
After 2½ years of growth an oyster is ready to reproduce and actually changes sex during it's life cycle. While in it's female stage the fertile Pinctada lays eggs all year. To ensure the survival of the species, each produces 40 million eggs over a lifetime. Conception depends on a chance encounter with spermatozoon. The developing larva are food for any sea life that eats plankton, including living coral. After they form bivalve shells they are called 'spats' and have to survive being prey for starfish, rays, octopus, and crabs.
It takes 4 years of diligent work to create lustrous Tahitian black pearls. They can only be produced by the giant black-lipped oyster 'Pinctada Magaritifera' (actually a bivalve mollusk) which is nick-named 'mother-of-pearl'. Pinctadas can grow to a diameter of 30 centimeters (the size of a dinner plate) and weigh 5 kilograms. Farming these fragile oysters requires continual care.
The creation of cultured Tahitian pearl begins with the collection of microscopic oyster spats. At 3 weeks old, a spat finds it's new shell too heavy for swimming, so it searches for a surface to attach to. A pearl farm sets out collectors that are ideal places for these tiny oysters to find refuge and mature. After about 2½ years, the oysters have grown big enough to start producing pearls.
An incision is made in the gonad (reproductive organ) to first implant graft tissue from another living oyster. This is a small piece of mantle, which will form a pouch around the nucleus to create the pearly coating, called nacre. Graft tissue is taken from the most colorful donor oysters to create pearls with the most beautiful colors.
Next, the nucleus is implanted. This is a piece of 6mm to 8mm spherical shell, which is usually Mississippi River mussel (especially cultivated for this purpose) from Tennessee USA. Some farms now use mother of pearl from Pinctada oysters for their nuclei and produce more grade A pearls.
So, how are pearls made? The oyster treats the shell implant as an invasive substance and secretes a black pigment (a type of calcium carbonate called aragonite) to protect its delicate reproductive system. This forms a surface of thousands of layers of lustrous nacre and is the magic that creates a treasured Tahitian black pearls.
This is a skilled operation and technicians must have a record of success to prove worthy of this important work. The expertise of the grafter is the most critical factor in producing a quality harvest. They are highly paid and booked years in advance. If the graft is mistakenly inserted between the coat and the shell, a half pearl will be formed. These sell for less, as they can only be used for rings and pendants. On family farms it is usual for family members to learn the trade and do the grafting.
After grafting, the oysters are attached to long strings inside protective wire baskets. These are hung back on lines that straddle the lagoon, about 7 meters below the surface. These lines are tied to supports that are anchored down about 40 meters, on the bottom of the lagoon. It takes 1½ years for the beauty and luster of Tahitian black pearls to be perfected, so that it can be harvested.
If an oyster has produced a quality pearl, a second nucleus is positioned when the previous pearl is gently extracted. This nucleus is aproximately the size of the pearl that has been removed. Some oysters can create 4 consecutive cultured Tahitian pearls, each one larger than the last. But the quality of the pearling nacre declines with the increasing age of the oyster.
Water temperature must be continually monitored. If a storm is likely, the strings of oysters are lowered deeper into the lagoon. In hot weather they are moved to a cooler place.
The oysters' shells must be kept clean so that they can properly filter their food, stay healthy and produce beautiful Tahitian black pearls. On some small farms the strings of oysters are hung from a platform in shallower water, every 3 months. This attracts the colorful lagoon fish who nibble the algae and other parasites that have attached themselves to the oyster shells. Another method is to manually remove unwanted organisms with a knife. Large farms use a high pressure hose to automate the process.
Now you know the the mystique surrounding, how are pearls made! It's a story of how man harnesses the combined efforts of animal and mineral to create prized 'jewels of the sea'. Find out how to recognize cultured Tahitian pearls.