Freshwater Pearl

Freshwater pearls are cultured mainly in lakes and ponds in China, often with many pearls grown in one mussel. Most Chinese farmers implant only pieces of mantle tissue, without a bead, which mainly yields baroque and other irregular shapes and occasionally rounds. Newer Chinese production also uses shell-bead nucleation, giving small near-round to round pearls that resemble akoya pearls.

Bead-nucleated freshwater pearls can look like saltwater akoya pearls, but names such as "Chinese akoya", "baby akoya" or "freshwater akoya" are incorrect according to GIA: they are freshwater pearls. Such pearls often show a very slightly flat side, but visual checks alone are often not enough. Laboratories separate freshwater from saltwater pearls by trace elements (manganese is typically higher in freshwater pearls, strontium in saltwater pearls) and by X-ray fluorescence imaging, under which freshwater pearls often glow moderately to strongly greenish yellow. Unnaturally bright colours usually indicate dye.

Pearl has a Mohs hardness of about 2.5, so it scratches easily. High heat can burn or crack pearls, and many chemicals and all acids, including hair spray, perfume, cosmetics and even perspiration, can damage them. Dyed pearl colours can change over time. Never use ultrasonic or steam cleaners; wipe the pearls with a very soft, clean cloth after each wearing, use warm soapy water only for occasional cleaning, and let a strung necklace's thread dry completely before wearing it.

Chinese rivers and lakes were among the outstanding sources of natural pearls before 1492, and the first steps toward pearl culturing occurred hundreds of years ago in China. In the early 1990s, Chinese freshwater pearl culturing was still in its infancy for higher-quality goods; by the mid-1990s the best Chinese freshwater pearls, now produced as 6–7 mm semi-rounds, began to rival mid-range akoya pearls.

Pearl, natural or cultured, is a US birthstone for June and is considered the gem of the third and thirtieth wedding anniversaries. According to GIA, pearls have always been associated with the mystery and life-sustaining nature of water, and in Europe they symbolized modesty, chastity and purity.

In ancient China, pearls were believed to guarantee protection from fire and fire-breathing dragons.