China is the number one producer of freshwater pearls, followed by Japan and the United States. Over 35 years ago, China’s highly lustrous rice pearls began appearing around the world, and since then the freshwater pearl industry has taken off.
Cultured freshwater pearl farmers in China have long been known to be able to produce mass quantities of cultured freshwater pearls at a relatively low price. However, advances in farming and culturing methods have improved the quality of the pearls. Until the last decade or so, most Chinese freshwater pearls were low-quality. Today, not only can they rival their saltwater counterparts, cultured freshwater pearls are produced in more popular colors and shapes.
Chinese Pearl Farming History
China has been in the pearl farming business since the 1200s! Ancient manuscripts describe blister pearl culturing methods that are very similar to the ones used today. Blister pearls are formed when a nucleus is inserted between the mussel’s mantle and its shell. What results is a pearl that grows attached to the shell. Eight hundred years ago, the Chinese cut these pearls from the shells to sell as ornaments.
In the 20th century, little was known about the Chinese pearl industry until around 1970 when producers flooded the market with what were known as “rice pearls. ” They were small and wrinkled but often were lustrous and iridescent, so these tiny gemstones found their way into many jewelry boxes.
Even 30 years ago, approximately 2 percent of the Chinese freshwater pearls were of high enough quality to compete with the freshwater pearls produced by Japan and the United States. There were enough of these inexpensive, high-quality pearls based on volume to put pressure on China’s competitors to improve their product.
The Japanese had success culturing round freshwater pearls for decades, and the Chinese freshwater pearl farmers began to focus more on quality than quantity. They soon began producing round, near-round and baroque freshwater pearls. Popular button and oval shapes, known as “corn” and “potato” pearls, became more common.
The industry continues to grow, but at a slow pace. This is chiefly due to the long period it takes to produce a freshwater pearl. Pearl development takes two to six years, which is a long investment period between nucleation and market.
Farms of Today
Most of China’s freshwater pearl farms are located in the valleys of the Yangtse River, as well as its tributaries. Most farms are located within 300 miles of Shanghai. There are thousands of family-run operations and a significant number of sophisticated, large- scale farms. Most farms, no matter how large, grow other products, whether it is ducks, rice or fish. It’s a symbiotic relationship between raising the mussels that produce pearls and other crops – powdered shells fertilize crops and manure nourishes mussels or the fish needed in the mussel-raising process.
The Chinese pearl farms face many hazards – floods, industrial pollution, weather and parasites. Another challenge is keeping ponds made for the mussels. Ponds fill in with mud anywhere between five and 15 years. The fish that live near the bottom and the mussels, left to develop pearls near the surface, have to be moved to another pond. The resourceful farmers either use the filled in pond for agriculture or will remove the mud and start over raising fish in the revitalized pond.
About 10 different species of mussels are nucleated to create pearls. These days, most use Chinese pearl farmers use H. cumingi mussels. The use of H. cumingi increased once farmers began focusing more on quality rather than quantity. However, C. plicata, which produces pearls the fastest, is still a popular choice.
Mussels are either farm-raised or bought at local and regional hatcheries. H cumingi is usually nucleated when it is six or seven months old. Nucleation occurs year-round, but many farmers choose to implant in April and May or August through October to take advantage of the best weather.
The nucleator makes 20 to 25 tiny incisions in two rows in mantle tissue in one of the mussel’s two valves, then inserts donor mantle tissue into the incisions. Turning the mussel over, the nucleator repeats the surgery.
Two to six years later, at harvest, the mussel will yield 30 to 40 cultured pearls. Harvest usually occurs in November, before winter. Pearls range from 2mm to 13 mm, but big sizes are rare. Most measure between 4 mm and 7 mm are mostly solid nacre. Some pearls will be hollow in the middle where the donor mantle tissue was, which will appear when the pearls are x-rayed.
After harvest, farmers return some of the mussels to the ponds if they produced good quality pearls. The pearl sac has already formed so no new mantle tissue has to be inserted. Second generation pearls aren’t usually as quality but they are usually good enough to be marketable.
Freshwater pearl farms try to increase the odds of round or near-round pearls by using a species of mussel more likely to produce a round pearl, maintaining quality water and inserting square pieces of donor mantle. The shape of the mantle tissue has a lot to do with the shape of the pearl that is produced, and the Chinese freshwater pearl farmers have found that perfectly square donor mantle is more likely to produce a round pearl. Only about 2 percent of the pearls end up round, but since the Chinese produce hundreds of tons of freshwater pearls, there are still an ample supply.
Some gemologists believe the best round or near-round freshwater cultured pearls are indistinguishable from the finest white Akoya cultured pearls. The freshwater pearls sell for much less.
The farmers have also determined what donor tissue is more apt to produce a specific color pearl. Chinese freshwater pearls are white, cream and other colors like yellow, orange and purple.
After harvest, the pearls are processed, which usually means bleaching. To restore luster afterwards, processors mix the pearls with grit, bamboo, walnut shells or wood and tumble them in machines.
Sometimes during processing the pearls are dyed, often to make them black. Other pearls are radiated or color-treated to create a more intense hue.
The Chinese freshwater cultured pearl industry continues to grow, thanks to changes in the government’s economic policies, which allow businesses greater freedom. The country has some geographical advantages, too. China is a large land mass with an abundance of rivers, streams and lakes, plus a wide variety of native mussels. With centuries of culturing experience and a low-cost work force, China will most likely continue to lead the freshwater pearl industry.
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