AKOYA PEARLS
Akoya pearls are cultured saltwater pearls which are cultivated from the oyster species Pinctada fucata martensii, primarily in China and Japan. Renowned for their luster, Akoya pearls are the pearls most often used in necklaces. They are generally white or cream coloured, and have overtone colours of rose, yellow, or green.
After the development of modern pearl culturing techniques by Kokichi Mikimoto in the early part of the 20th century, akoyas from Japan became the first pearls to be cultured on a large scale. They continue to be popular today, although production of Japanese akoyas has declined somewhat in recent years, due to water pollution and disease.
In recent years the Chinese have overtaken the Japanese in akoya pearl production. The Chinese began culturing akoya pearls in the early 90's, but had limited success until recent years. For more than a decade Chinese akoya pearls have been considered vastly inferior to this Japanese counterparts, but as experience and more advance technologies have become more common place the Chinese are now producing akoya pearls of qualities that rival that of the Japanese.
Due to the increased pressure of the Chinese competition many Japanese pearl farmers have focused much of their attention on culturing large akoya pearls, as quality akoya pearls larger than 8mm are a rare find in China. In lieu of farming smaller pearls, many Japanese factories now import their smaller akoya requirements from neighboring China. The pearls are treated and strung in Japan so that they may still carry the mark 'Made in Japan'. It has been reported that more than 80% of the pearls 7mm and smaller have come from Chinese farms regardless of whether or not they are sold by Japanese suppliers.
The akoya oyster is the smallest pearl-producing oyster, so akoya pearls also tend to be small, ranging in size from about 2 to 11 millimeters. They also tend to be the most consistently round and near-round pearls, making them ideal in terms of matching for multi-pearl jewelry such as strands, bracelets, etc.
FRESHWATER PEARLS
Although the traditional source of pearls has been oysters which live in saltwater, mollusks which live in freshwater lakes and rivers can also produce pearls. China has harvested freshwater pearls for many a millennia. The first record mentioning pearls in China was from 2206 BC. The United States was also a major source of freshwater pearls from the discovery of the New World up through the 19th century, when over-harvesting and increasing pollution significantly reduced the number of available pearl-forming mussels.
Freshwater pearls are often somewhat less lustrous than their saltwater counterparts. However, they appear in a wide variety of shapes and colors, and they tend to be less expensive than saltwater pearls, making them quite popular. Freshwater pearls are also quite durable, resisting chipping, wear, and degeneration.
Freshwater pearls differ from other cultured pearls in that they are not bead-nucleated. Freshwater mollusks are nucleated by creating a small incision in the fleshy mantle tissue and inserting a piece of mantle tissue from another oyster. This process may be completed 25 times on either side of the mantle, producing up to 50 pearls at a time. The mollusks are then returned to their freshwater environment where they are tended for 2-6 years. The resulting pearls are of solid nacre, but without a bead nucleus to guide the growth process, the pearls are rarely round.
In recent years the Chinese have been able to take the art of culturing freshwater pearls to new levels. In the last decade the quality of pearls produced have become so high that many pearls in the top percentage of a harvest are nearly indistinguishable of their saltwater relatives. Gone are the rice-shape seed pearls as they are now being replaced with round, lustrous pearls of sizes as large as 16mm, mimicking large South Sea pearls. This has created a renewed interest in freshwater pearls as an affordable alternative to the higher priced saltwater.
The Japanese have a distinguished history of culturing freshwater pearls as well. Lake Biwa was once world renowned for producing high-quality freshwater pearls. However, in the mid 1970's pearl farming all but came to a halt due to pollution in this lake that was once synonymous with freshwater pearls. Today the Japanese are trying once again to farm freshwater pearls in Lake Kasumigaura, utilizing a bead-nucleated hybrid mussel ( Hyriopsis Schlegeli anadonata/plicata hybrid mussels). The resulting pearls have been quite large and unique. But due to the high prices of such pearls the market remains a niche for collectors.
Shell Pearls
A shell pearl is made from the shell of an oyster and a mother of pearl bead which is coated and polished to the final shape of the pearl required. The mother of pearl adds weight, value and durability to the pearl. The materials used in order to make shell pearls are the same materials from which cultured pearls are made.
