However, it remains difficult to obtain precise data on annual production, pearl quality, and the farming methods employed. China is home to thousands of pearl farms using highly diverse techniques.

In this article, the authors report on their visits to several pearl farms in the province of Hanzhou, where they observed new grafting techniques using mantle tissue fragments — and, more rarely, small spherical nuclei made of nacre or wax. Thanks to improved techniques and the use of younger Hyriopsis cumingi, Chinese producers are now able to produce larger, rounder pearls, with more varied colors and a stronger luster. Pearls resulting from mantle grafting can be distinguished from nucleated pearls by X-ray examination.

The demand for these pearls continues to grow on the global market. They are available in sizes ranging from 2 to 10 mm, in a wide variety of shapes (round, oval, baroque, pear, button) and in rich colors ranging from orange to purple, sometimes with a metallic sheen. The vast majority of pearls produced in China come from grafts without spherical nuclei, which distinguishes them from freshwater cultured pearls from other regions.

Conclusion:

China’s annual production is estimated at about 1,000 tons, of which 650 tons are suitable for jewelry. As the sector is in a phase of rapid expansion, a significant increase in production is expected in the coming years. While a growing share of higher-quality pearls is entering the market, the majority remain of medium to low quality.

The recent progress observed — in size, surface, luster, and color — is the result of several technical advances:

• Replacement of the Cristaria plicata mussel by H. cumingi;
• Grafting on younger specimens;
• Optimized implantation techniques, using a reduced number of mantle fragments;
• Longer growing periods before harvest;
• More frequent rotation of farming sites.

Grafting techniques with spherical nuclei have also improved, but remain marginal due to their high cost and the complexity of the process (two steps instead of one). Modern X-ray technology now makes it possible to distinguish these different categories of pearls without ambiguity.

The authors believe that the data collected provide an accurate picture of the Chinese freshwater pearls currently available on the market and that ongoing technical innovations will make it possible to offer higher-quality products in the future.