Pearl

A pearl is a hard, glistening object produced inside the soft tissue of a living shelled mollusk or similar animal. Just like the shell of a mollusk, a pearl is made of calcium carbonate, forming tiny crystals that build up in layers. Pearls come in many shapes—some are perfectly round, while others, called baroque pearls, have unusual, freeform shapes.

Natural pearls form on their own in the wild, but they are very rare. Most pearls sold today are cultured, meaning they are grown in special farms using pearl oysters or freshwater mussels. These cultured pearls look almost identical to natural ones and make beautiful gemstones. Pearls have been treasured for thousands of years because they are rare, shiny, and valuable, often symbolizing something special and admired.

People have used pearls not only in jewelry but also in cosmetics, medicines, and even paint. Though most pearls come from mollusks, almost any shelled creature can produce a type of pearl, though these usually aren’t as shiny or valuable. Whether natural or cultured, pearls remain one of nature’s most beautiful and prized creations.

Etymology

The English word pearl comes from the French perle, which originally came from the Latin word perna meaning 'leg'. This is because the shape of the bivalve that makes pearls looks like a ham- or mutton leg.

The scientific name for the family of pearl-bearing oysters, Margaritiferidae, comes from an Old Persian word for pearl, *margārīta-. This word is also the source of the English name Margaret.

Definition

All shelled mollusks can produce a kind of "pearl" when something tiny and irritating gets trapped inside them. However, most of these are not valuable like gemstones. The most famous and valuable pearls are called nacreous pearls, made by special groups of bivalves or clams from layers of nacre.

Natural pearls, which form without any help from humans, are very rare. In the past, people had to collect and open many pearl oysters or mussels to find just one natural pearl, which made them very expensive. Today, many pearls are cultured pearls, which are made on farms with human help mixed with natural processes. Some pearls come from saltwater pearl oyster and others from freshwater mussels like the freshwater pearl mussel.

Physical properties

The shine of pearls, called luster, comes from how light reflects, bends, and spreads out from their layers. The more thin layers a pearl has, the better its shine will be. Pearls can also show colorful patterns because of how their layers overlap. Some pearls, especially those grown in special ways, can be colored yellow, green, blue, brown, pink, purple, or black. The most prized pearls have a bright, metallic shine.

Since pearls are made mostly of calcium carbonate, they can dissolve in vinegar. This is because the tiny crystals in the pearl react with the weak acid in vinegar, creating calcium acetate and carbon dioxide gas.

Freshwater and saltwater pearls

Freshwater and saltwater pearls may look similar, but they come from different places. Freshwater pearls form in special mussels called Unionidae that live in lakes, rivers, and ponds. These mussels can be found in both warm and cool places, including Scotland. Most freshwater cultured pearls come from China.

Saltwater pearls grow inside pearl oysters, family Pteriidae, which live in the ocean. These oysters are often cared for in special areas like lagoons or volcanic islands to help make pearls.

Formation

The mantle, or protective membrane, of a mollusk deposits layers of calcium carbonate in the form of the mineral aragonite or a mixture of aragonite and calcite, held together by an organic compound called conchiolin. This combination is called nacre, which makes up mother-of-pearl. Natural pearls form when tiny intruders, like parasites or bits of organic material, enter the mollusk. The mollusk reacts by forming a pearl sac and covering the irritant with layers of calcium carbonate and conchiolin, creating a pearl over time.

Cultured pearls are created by placing a tiny piece of mantle tissue from another shell into a host shell, which then forms a pearl sac and produces a pearl. There are different methods for culturing pearls, using either freshwater or seawater shells and sometimes adding a small bead as a nucleus. Cultured pearls can be identified from natural pearls using special tools like X-ray machines.

From other species

Many types of shelled animals can make pearls, but most of these are not very shiny or beautiful. They are usually not valuable except to scientists or collectors. These pearls can be found in mussels, oysters, and snails.

Some species, like the bailer shell, giant clam, and abalone, can make pearls that are more attractive. Abalone pearls from New Zealand, called "blue pearls," are known for their bright colors. Another rare pearl comes from the queen conch in the Caribbean Sea, often pink in color. The largest known pearl came from a giant clam in the Philippines, measuring 30 cm wide and 67 cm long.

History

Pearl hunting

Pearl hunting is an ancient practice dating back thousands of years. Records from Sri Lanka mention pearl gifts given to kings and emperors. Divers in the Indian Ocean, including areas like the Persian Gulf and the Gulf of Mannar, have collected pearls for a very long time. In China, pearl hunting began during the Han dynasty in the South China Sea.

When Spanish explorers arrived in the Caribbean, they found large pearl beds near Cubagua and Margarita. One famous pearl, called La Peregrina pearl, was so beautiful that a king kept it for himself and it became part of the Spanish Crown Jewels.

Pearl farming

See also: Oyster farming

Today, most pearls sold are cultured, meaning they are grown with help from humans. There are two main types: beaded cultured pearls, like akoya, South Sea, and Tahitian pearls, and non-beaded freshwater cultured pearls.

The process of growing cultured pearls was developed by scientists and brought to Japan, where it became a big business. This method involves placing a small piece of shell and tissue into a pearl oyster, which then makes a pearl around it. This has made it possible to produce many beautiful pearls for people to enjoy.

Timeline of pearl production

Mitsubishi started growing pearls in 1916 using a special type of oyster. Although there were some challenges along the way, pearl farming grew after World War II. Today, places like Australia, the Philippines, Myanmar, and Malaysia are important for producing beautiful, large pearls.

In recent years, China has become a big producer of a type of pearl called akoya pearls. Japan still plays a key role in processing and exporting these pearls, even though it now imports many from China. The largest pearls come from a special oyster found in the Pacific and Indian Oceans, known for their big size and shiny appearance.

Freshwater pearl farming

In 1914, people started growing cultured freshwater pearls using mussels from Lake Biwa in Japan, near the city of Kyoto. These pearls were called Biwa pearls. However, pollution made it very hard to keep making them.

Today, China makes the most freshwater pearls in the world, producing over 1,500 metric tons each year. In the United States, a pearl farm in Tennessee became a popular place for tourists to visit, even though it no longer makes pearls for sale.

Momme weight

Many pearl dealers and sellers use a special weight measure called the momme. This unit comes from Japan and has been used there for many years. One momme equals 3.75 grams, and it helps people know if a pearl necklace is the right size and shape.

In the past, especially in the United States, the momme was also used to measure the quality of silk cloth. For big pearl necklaces like those from the South Sea and Tahiti, the momme weight is very helpful to buyers.

In jewelry

The value of pearls in jewelry depends on their luster, color, size, smoothness, and symmetry. Luster, or the way light shines on the pearl’s surface, is the most important factor. Bigger pearls are usually more valuable, especially if they are perfectly round, which is rare. Teardrop-shaped pearls are often used in pendants.

Pearls come in many shapes. Perfectly round pearls are the rarest and most valuable. Semi-round pearls can be used in necklaces, while button-shaped pearls are often used in earrings or single pendants. Pear-shaped and baroque pearls, which have unique, irregular shapes, are popular in necklaces and earrings. The length of pearl necklaces has special names: a collar sits close to the throat, a choker sits at the base of the neck, a princess length reaches the collarbone, a matinee length falls just above the chest, an opera length reaches the breastbone, and a pearl rope is longer than an opera length. Pearls can also be white, black, or many other colors, with some rare colors coming from the ocean.

Religious references

The word "pearl" appears in many religious writings and traditions. In Hindu traditions, pearls are considered sacred. The Hindu book called the Garuda Purana talks about special "Nine Pearls." Pearls have also been worn by kings and linked to Hindu gods like Lord Vishnu.

In the Hebrew Bible, pearls are mentioned as valuable treasures. The New Testament includes a famous story where Jesus compares the Kingdom of Heaven to a very valuable pearl. The city of New Jerusalem is described as having gates made of giant pearls.

The Quran, Islam’s holy book, describes people in paradise wearing beautiful pearls as jewelry. Many other religious poems and writings also use pearls as symbols of great worth and beauty.