In ancient times these “gems of the sea” adorned royalty, aristocrats and the very wealthy. In early Asian societies, pearls were viewed as physical symbols of purity, chastity and feminine charms. As early as 2500 BC, there was a substantial pearl trade in China. Later the jewels found their way to India, Egypt, Persia and Rome. The lure of pearls brought Spanish adventurers to America, who heard reports of the vast pearl treasures held by Indians. In fact, Native American burial mounds in the Ohio River Valley were found to contain huge quantities of freshwater pearls dating back to as early as 200 BC.
According to historians, in the Roman period pearls were prized by both men and women. The gems were considered so valuable in some cultures that their ownership was restricted by law. American Indians used freshwater pearls to create jewelry, headdresses, figurines and other treasured objects.
The most famous pearls in the world are the largest, rarest and most beautiful. The Hope Pearl weighs 4.50 carats and is two inches long. It is on display at the South Kensington Geological Museum in London. La Pellegrina, which is displayed in the Museum of Zazima in Moscow, weighs in at 27.9 carats. The Miracle of the Sea is the largest pearl in existence, weighing a whopping 297.8 carats!
Pearls are produced by mollusks – the common name for a phyllum of soft-bodied animals that usually have a hard shell. Specifically, pearls are created by the class of mollusks known as bivalves, which include clams, oysters, mussels and scallops. In saltwater, pearls are formed by oysters, while in freshwater lakes and rivers, they are produced by mussels. Natural saltwater (also called Oriental) pearls are formed when sand or shell particles are caught in an oyster’s “beard” as it moves along the sea floor. The irritant settles in the soft body of the mollusk between the shell and the mantle. The oyster (not the edible variety) secretes fluid to protect its body from the irritation. This secretion, called nacre (pronounced nay-ker), gives pearls their iridescent color. Nacre surrounds the particle (known as the “nucleus”) in concentric layers, which build up to create a richer and deeper luster.
Over the centuries, traditional harvesting techniques proved very time-consuming and produced few jewelry-quality pearls. Divers descended to the ocean floor armed only with a knife and a basket. The diver cut each oyster loose from the plants surrounding it and placed it in the basket. After 3-5 minutes of harvesting, the diver returned to the surface and emptied the basket of oysters. The few gem-quality pearls recovered varied in size, shape, color and quality, making it nearly impossible to find similar or matching pearls for a necklace or earrings.
Before oil became the preferred commodity, the Persian Gulf supplied most of the world’s saltwater pearls. Today, saltwater pearls are found along the coasts of Africa, Australia, Spain, Portugal, Japan and the South Seas. Native Americans of the Atlantic coastal areas and the Mississippi River basin were the first to collect and use freshwater mussel pearls in America. Today, freshwater pearls are cultivated in 31 United States.
Cultured pearls are defined as pearls created by oysters through the inducement of man. They have become highly desired because of their uniformity in size and shape. They are genuine pearls – cultivated with a little help.
Many attempts were made over the years to entice oysters to produce a greater number of high quality pearls. But success didn’t come until the 20th century. In the early 1900s, three Japanese men working independently discovered a method of inducing pearl growth that gave rise to the modern cultured pearl industry.
Most of the world’s cultured pearls are produced in Japan, Australia and the South Seas. A skilled technician opens the live oyster, makes a small incision in the mantle (tissue) and inserts a nucleus. The nucleus usually consists of crushed bits of oyster shell. More than one nucleus is inserted into each mollusk during this procedure, thereby increasing the chance of creating a viable pearl.
Following the insertion, the oyster is placed in a tray of water to rest. The live oysters are then transferred to a cage and lowered into the sea to live while the nacre builds the pearl.
When this method was first developed, pearls were allowed to incubate for three years. Today, most pearls are harvested after six to eight months, which affects the size and shape. Higher quality pearls still take between one and three years to form.
Pearls are measured in millimeters across the diameter of the pearl. Most pearls sold in the U.S. are between 5mm and 7mm in diameter.
Once removed from the oyster, pearls are first sorted by size and then by color and shape. Because they are created by nature, pearls will have their own birthmarks – blemishes or irregular surfaces. Pearls with only a single blemish will be used for earrings, cuff links and tie tacks. If a pearl has blemishes on opposing sides, a hole will be drilled through the middle so the pearl can be strung for use in necklaces.
Pearls of similar size, shape and color are strung together with silk thread. The thread is knotted at the drilling point to prevent the pearls from rubbing against each other and destroying the natural luster. This practice also gives the necklace more flexibility and prevents the loss of more than one pearl should the string break.
Seven key factors define the quality of a pearl. Here’s how each one affects the value and beauty of pearl jewelry.
The quality of the drilling in the strand is also important. Pearls that are drilled off-center will hang out of line with the rest of the strand, thereby decreasing beauty and value.