Pearl

A pearl is a hard, shiny object made inside a living shelled mollusk or similar animal. Like the shell of a mollusk, a pearl is made of calcium carbonate, forming tiny crystals that build up in layers. Pearls can be many shapes—some are perfectly round, while others, called baroque pearls, have unusual shapes.

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

People have used pearls not only in jewelry but also in cosmetics, medicines, and paint. Almost any shelled creature can make a type of pearl, though these are usually not as shiny or valuable. Whether natural or cultured, pearls are one of nature’s most beautiful and prized creations.

Etymology

The English word pearl comes from the French perle. That French word came from the Latin word perna, which means 'leg'. This is because the shape of the bivalve that makes pearls looks like a 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 make a kind of "pearl" when something tiny gets stuck inside them. But most of these are not valuable like gemstones. The most famous and valuable pearls are called nacreous pearls. They are 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. They are made on farms with some help from humans 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 layers a pearl has, the better its shine will be. Pearls can also show colorful patterns because of how their layers overlap. Some pearls can be 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 layer, of a mollusk adds layers of calcium carbonate as the mineral aragonite or a mix of aragonite and calcite, bound by a material called conchiolin. This mix is called nacre, which is mother-of-pearl. Natural pearls start when tiny things, like parasites or bits of material, get inside the mollusk. The mollusk then makes a pearl sac and coats the irritant with layers of calcium carbonate and conchiolin, forming a pearl over time.

People make cultured pearls by putting a small piece of mantle tissue from another shell into a host shell. The host shell then makes a pearl sac and grows a pearl. There are many ways to culture pearls, using either freshwater or seawater shells and sometimes adding a small bead as a core. Tools like X-ray machines can tell cultured pearls apart from natural ones.

From other species

Many shelled animals can make pearls, but most are not very shiny or beautiful. They are usually only valuable to scientists or collectors. These pearls come from mussels, oysters, and snails.

Some animals, like the bailer shell, giant clam, and abalone, can make more attractive pearls. 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. It was 30 cm wide and 67 cm long.

History

Pearl hunting

Pearl hunting is an ancient activity that has existed for thousands of years. Records from Sri Lanka talk about pearl gifts given to kings and emperors. Divers in the Indian Ocean, such as in 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 reached the Caribbean, they discovered 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, which means 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 way to grow cultured pearls was created by scientists and became popular in Japan. This method puts a small piece of shell and tissue into a pearl oyster, and the oyster then makes a pearl around it. This has helped make many beautiful pearls available for people to enjoy.

Timeline of pearl production

Mitsubishi began growing pearls in 1916 using a special kind of oyster. Pearl farming grew after World War II. Today, places like Australia, the Philippines, Myanmar, and Malaysia are important for making beautiful, large pearls.

In recent years, China has become a big producer of 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 began growing cultured freshwater pearls using mussels from Lake Biwa in Japan, close to the city of Kyoto. These pearls were named Biwa pearls. But pollution made it very difficult to continue making them.

Today, China produces the most freshwater pearls in the world. In the United States, a pearl farm in Tennessee is a popular spot for tourists to visit, even though it no longer makes pearls to sell.

Momme weight

Many pearl 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. It helps people know if a pearl necklace is the right size and shape.

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

In jewelry

Pearls are special in jewelry because of their shine, color, size, smoothness, and shape. The way light shines on a pearl, called luster, is the most important thing. Bigger pearls are often more valuable, especially if they are perfectly round, which is hard to find. Pearls that look like teardrops are often used in necklaces that hang from the neck.

Pearls come in many shapes. Perfectly round pearls are the rarest and most valuable. Semi-round pearls can be used in necklaces, and button-shaped pearls are often used in earrings or single pieces that hang from the neck. Pear-shaped and baroque pearls have unique, irregular shapes and are popular in necklaces and earrings. Necklace lengths have 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 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.