How do pearls appear in a shell?

Pearls are a true miracle of nature, an incredibly mysterious and precious stone. For many years, humanity has been creating amazing jewelry from it, which is distinguished by its delicate and fragile appearance, captivating with its sophistication and uniqueness. Below we will look at how pearls are formed.

How are natural pearls obtained?

We need to start with the fact that according to the method of formation, pearls are divided into 2 categories – natural and cultured. Natural is formed in mollusk shells. More precisely, pearls are the result of self-defense of mollusks. When a foreign object gets into the sink, it is enveloped in a special substance. So, layer by layer, pearls are formed. It protects the mollusk from foreign objects, reduces friction and reduces irritation. It is worth noting that pearls come in freshwater and seawater varieties. The first option is considered more universal and widespread. Freshwater pearls are quite easy to obtain and are therefore inexpensive. However, their sizes are somewhat smaller than their marine counterparts. In addition, they have an irregular shape and a distinct color. It should be emphasized that the most expensive pearls are produced by marine mollusks of the genus Pteria and Pinctidae.

How are artificial pearls made?

People began diving for pearls more than 4000 years ago. They had to dive to a dangerous depth of up to 20 meters without any insurance. In 1-2 minutes they had to collect as many shells as possible. There could be up to 30-40 such dives per day. It should be noted that the divers had only a knife at their disposal, and bloodthirsty sharks lay in wait around them. So, when people understood how pearls appear in nature, they began to obtain them artificially. The Japanese Kokichi Mikimoto was the first to do this in the 90s of the XNUMXth century. He was the first to open a company for growing this precious stone. What is the essence of artificial extraction: the shell flaps are slightly opened, foreign bodies (for example, beads) are placed inside, and then the shell is placed in a special reservoir. There, all conditions for the capricious mollusks to live are created in advance. It should be noted that it takes up to 2 years to grow a large river pearl, and up to 3 years for a sea pearl. Pearls grown this way are called cultured pearls. As a rule, it is used in most modern jewelry. The properties of the cultivated species are absolutely the same as those of the natural one, but the cost is much lower. The main suppliers of this stone are Japan and China, less often – Polynesia and Australia. The online store “Lavka Masterov” is ready to offer beads made from natural stones.

Popular types

• Kasumi. This stone can only be found in the vicinity of Lake Kasumigaura in Japan. It is produced by oysters specially bred in the 90s of the last century. Kasumi attracts with its teardrop-shaped shape, fairly large size (up to 2 cm), and spectacular shine. This species is often used to make jewelry.
• Keshi. Both freshwater and sea oysters can produce pearls. Typically, keshi is a natural species because oysters do not accept artificial implants. It has a flattened shape. Reminds me of a flower petal. Very prized by jewelers.
• Souffle. This name was coined by jewelry expert Jack Lynch. The stone is obtained as follows: earthy, dry material is placed into the pearl sac of the oyster, which gradually swells and stretches the sac. At this moment, the oyster grows nacre around the core, resulting in a large pearl. The cost of the stone in this case depends on the thickness of the mother-of-pearl layer.
• Blister. The stone has a unique structure, as if inflated from the inside with bubbles. Unique jewelry is made from it.
• Conc. Quite a rare species, which is especially valued by jewelers. The stone has a spherical or oval shape. It can be presented in a variety of colors – yellow, soft pink, white, brown. It is worth noting that conch shellfish live only in the Caribbean Sea. These pearls cannot be cultivated, since when the shell is opened, the animal dies.

The online store “Lavka Masterov” is ready to offer pearl beads of various types.

Primary colors

Classic pearls are always presented in white with some blue tint. However, the shades of this stone cannot be taken strictly and unambiguously. There are more than 120 species in nature. These are gold, green, pink and other colors. But they are, of course, less common than white.

On what factors does color depend? From the composition of the water in which the mollusk lives; from surrounding climatic conditions; from the type of mollusk itself, in whose shell the pearls are grown. It is believed that soft pink stones are most often mined in India, white and silver in Australia, and brown in Mexico. But Polynesia boasts black, blue and purple shades.

Once mined, pearls are often bleached and dyed specific colors. The freshwater variety stains quickly and easily because it has a thin layer of mother-of-pearl. And it may even take several months to paint sea stones.

Pink and black stones are most valued, and yellow stones are less valued.

In-demand jewelry

Now you know what pearls are made of and what shapes and colors they can come in. What kind of jewelry is it used in? In pendants, earrings, rings, beads and bracelets. Icons are also embroidered with it.

The demand for pearl jewelry never goes away. Even in Ancient Egypt, the first beauties believed that this stone was capable of giving youth and beauty for many years. Almost all of Cleopatra’s jewelry had pearls.

Modern researchers say that pearls help with depression, insomnia, and hypertensive crisis. It has a positive effect on the nervous system. And a good mood is guaranteed to everyone who receives pearl jewelry as a gift!

“Each pearl is a small Moon. How does it get into mollusk shells? Yes, it’s very simple – when on clear moonlit nights the Moon is reflected in reservoirs, its rays acquire fluid properties, and the lunar substance, “flowing” to the bottom of the reservoirs, penetrates the open shells and curls up. It is in these shells that divers subsequently discover pearls shimmering with a matte light.” – this is how one of the most poetic legends that surround the origin of pearls among the peoples of the world tells about the origin of pearls. But how is it actually formed? And what types of pearls are there?

What is a pearl?

Pearls – round or irregular in shape formation of biogenic origin, extracted from mollusk shells. Pearls contain the mineral aragonite (chemically it is calcium carbonate, one of its polymorphs) and is valued as a precious stone.

Pearl formation occurs inside the shells of freshwater and marine mollusks. Almost all types of mollusks can produce pearls, however, this phenomenon has not been detected in some representatives (spatiopods, armored mollusks, monoplacophorans).

The main industrial source of pearls is considered to be the shells of bivalve mollusks – both marine and freshwater, including the giant tridacna; despite the fact that its shell is devoid of a layer of mother-of-pearl, pearls of milky white or pink color are found in them.

Pearls and mollusks belonging to the order Gastropods are produced, in particular, blue-green, with a strong glassy sheen; irregularly shaped pearls are produced by representatives of the Haliotis family.

How are pearls formed?

The mantle of bivalve mollusks has the form of a double fold, “hanging” from the back on the sides to the ventral side. The outer layers of the mantle contain large quantities of special cells that produce substances that make up the layers of the shell walls. Normally, these cells produce the nacreous layer of the shell. The shell, which is a kind of home for the mollusk, does not close hermetically, so grains of sand, specks, small air bubbles, and even parasitic microorganisms get into it from time to time.

By enhancing the production of nacre, the mollusk surrounds the foreign body with it, smoothing out all the irregularities on its surface, turning any speck into a jewel.

When a foreign body appears in the mantle area, nacre produced by these special cells envelops it in concentric layers and, thus, isolates the mollusk from the body, simultaneously creating the beginning of the future pearl. If a foreign body gets between the mantle and one of the shell shells, the pearl, as a rule, fuses with its nacreous layer. When a grain of sand gets inside the mantle, a so-called free pearl is formed, which, as a rule, has a round shape.

Another prerequisite for the formation of pearls is the penetration of epithelial cells into the connective tissue of the mantle, which, by dividing, form a cyst (“pearl sac”) and subsequently, secreting nacre, ensure the formation of a spherical pearl.

Pearl formation occurs in the following areas of the mollusk body:

• thickened edge of the mollusk mantle;
• the muscle that closes the shell valves;
• directly below the apical depression, in the upper part of the mantle.

Cells of the nacre-producing epithelium can get here in various ways. In some cases, epithelial cells are brought in by any traumatic foreign elements (this could be, for example, shell fragments, grains of sand, parasites trapped inside the shell); in others, the epithelium is capable of forming a pearl without the participation of foreign particles (this occurs when the nacre-producing epithelium is brought inside the connective tissue of the mantle as a result of any traumatic effects, mechanical damage from the outside). In addition, secreting cells can enter the mantle as a result of various pathological processes within the body of the mollusk itself.

Why are pearls different?

The shape of a pearl is influenced by its location in the shell.: if it grows on the body of a mollusk, without contacting the shell valve, then its shape will be spherical, or almost spherical; if it comes into contact with the sash, the result will look like a growth.

The color and degree of shine of a pearl depends on the thickness of the mother-of-pearl layer, the thickness and transparency of the underlying layer, impurities in the aragonite from which it consists, from the type of water, from the geographical location, from the condition of the mollusks themselves, and sometimes from impurities in the water. The rarest, and, as a result, expensive, is the blue pearl found off the coast of Indonesia.

Having a fairly complete understanding of how pearls are formed, presenting in detail the mechanisms and patterns of this process, modern specialists quite successfully grow this mineral in the territories of special “plantations” by breeding pearl oysters – this method is much more effective than traditional fishing. Plantations are shallow coastal backwaters with warm water, where mollusks feel comfortable and safe – a kind of incubator.

Without relying on the mercy of nature, “farmers” carefully open the shell and place the base for the future pearl in it – small fragments of shells, beads and other similar objects can be used for this.

In the body of the mollusk, the process of isolating the foreign body is thus started by covering it with nacre.

Varieties of pearls, distinguished according to their origin:

• Natural sea pearls – the rarest and, therefore, the most expensive variety, mined in the southern seas off the coasts of Japan, Sri Lanka, and the Persian Gulf. The search for bivalve shells on the seabed, and then for pearls in them, is carried out by professional pearl divers. Finding a shell with a pearl is considered good luck, and beautiful, regular-shaped shells with a smooth surface are a rather rare catch;
• Natural freshwater pearls – a cheaper variety, since it occurs more often, is easier to obtain, and pearls in shells are found more often, sometimes several at a time. Freshwater “pearl” mollusks live in the rivers of Europe, China, and America. Freshwater pearls are smaller than sea pearls, often irregular in shape, and less shiny.

These two varieties are also called “natural” or even “wild” pearls.

• Cultured pearls (“tamed”) – essentially the same as the sea, but its acquisition is not planned and is carried out purposefully, in contrast to random production;
• Imitation pearl — these are beads imitating mother-of-pearl mineral, coated with paint of the appropriate color; material and size can be very different.

A pearl grows fastest in the first year of its existence – up to 2-3 millimeters per year. Subsequently, the growth rate slows down significantly and amounts to about less than half a millimeter per year.

The larger size of sea pearls compared to river pearls is explained by the more saturated biochemical composition of sea water. But river mollusks are much more “fertile”.

The formation of pearls in the shell is, in essence, a protective reaction of the mollusk body, which develops when a foreign body enters the mantle or the space between the mantle and the shell; an attempt to neutralize a foreign particle, as if to isolate oneself from it. It was this way of coping with minor troubles that made mollusks living in shells the subject of hunting by people.