Tips for stone care

How to distinguish sea pearls from river ones?

Natural pearls (those born without human intervention) are among the rarest gemstones and are therefore priced accordingly; these single pearls are usually sold at auction and purchased by collectors. Currently, most pearls sold on the market are cultured. “Cultured” pearls are grown with human help in conditions similar to nature, on special farms where the shells are monitored and cared for. Today, 99% of the pearls on the global jewelry market are cultured pearls. Cultured pearls are the same as natural pearls, as they are grown naturally in pearl oysters, but only under human control and assistance. When culturing pearls, a person places a nacre-shaped ball of irritant called a “nucleus” into the body of the oyster, after which the pearl formation process continues in the same way as when forming a natural pearl. It is a mistake to consider cultured pearls to be artificial. The process of culturing pearls is an extremely complex and delicate process that takes up to 3-8 years. People who grow pearls are practically deprived of the opportunity to in any way influence the process and result of the growth of the pearl, and cannot know what the finished pearl will look like, and also cannot guarantee that the mollusk will not reject it ahead of time. Not all grown pearls meet established quality standards – there is a fairly high percentage of defects in this risky business. The final result mainly depends only on nature.

Methods of growing pearls:

  • Nuclear (a seed nucleus is placed in the shell; the method is used to obtain sea pearls)

  • Nuclear-free. The second method is more inexpensive and has become most widespread in the cultivation of freshwater pearls, especially in China.

Nuclear method. How does this happen? First, a donor pearl oyster is selected. Most often this is a young pearl oyster with a good mantle – that is, a nacreous shell. The recipient pearl mussel must have a well-developed gonad (the so-called reproductive gland that secretes nacre). The shell with it is opened with pliers, and then a delicate surgical operation is performed: with specially designed instruments, an incision is made in the soft tissue and a graft is inserted into it – part of the mantle of the donor pearl oyster. A ball 6-9 mm in diameter, extracted from a bivalve freshwater mollusk, is placed next to it. After this, the pearl mussel goes back to the lagoon, where it spends another two years in peace. This is the most dangerous time: she may die or throw out the core (the same ball) – the probability of this is very high. If everything goes without complications, after a few years you get pearls. One of the external advantages here is the ideal surface of the pearl, because mother of pearl grows in a thin layer on a smooth artificial ball. The actual thickness of nacre on such pearls is from 0.2 to 1 mm. Such a 10-mm pearl grows in just a year (!). Such pearls can be called natural only with great reserve. When you take it in your hand, it instantly heats up, like any piece of plastic – even an inexperienced person will immediately distinguish a real, weighty and cold pearl from its weightless, easily warmed-up plastic imitator.

Nuclear-free way. The advantages of another method of growing pearls are that with a sufficiently small grain of sand and prolonged growth, cultured pearls are in no way inferior, and often surpass natural ones – in size and color. Today, most freshwater pearls, the size of which does not exceed 8-9 mm, are grown using nuclear-free technology, where a grain of nacre sand taken from the shell itself is used as a seed nucleus.

Cultured pearls

Cultured pearls are divided into freshwater (river) and sea, depending on the habitat of the mollusk.

Freshwater or river pearls. Freshwater or so-called “river” pearls grow in fresh river or lake water, even in former rice fields in China. The fields are flooded with water, and a very comfortable microclimate has developed there for mollusks, in which they quickly reproduce and bear beautiful pearls. “Pearl farmers” constantly monitor the water temperature, its composition and pH. During the ripening process, shellfish pearls must be turned over from time to time so that the pearl does not turn out “one-sided”. Those. no matter how you look at it, round pearls are still obtained with the hardest work, even in the “greenhouse” conditions of the farm. Freshwater pearls are very popular due to their variety of shapes, colors and sizes. Sizes ranging from 2 to 8 mm are found, however, the average size is from 4 to 6 mm. The absolutely rare size of freshwater cultured pearls is more than 10 mm, so the price of such pearls increases dramatically!

“Hyriopsis schlegeli” is the most common freshwater shell and comes from the Unionide family. The outer sides are usually brown, however, the inner sides are smooth and white. Freshwater pearls, unlike saltwater pearls, do not have a core. The exception is pearls whose size exceeds 10 mm. If 1,5 years have passed, the pearl reaches approximately 3 mm. After 3 years it can already reach 7 mm. Freshwater pearls will only be larger than 7 mm if you wait another 4 years. This means that pearls more than 10 mm in diameter grow for more than 7 years.

The following colors of freshwater pearls are found: white, cream, champagne, orange-pink, lilac, light purple and brown.

Shapes from oval, ovoid, teardrop-shaped to potato-shaped. Perfectly round, large pearls are absolutely rare.

Saltwater pearls (pearls grown in salt water). Saltwater pearls are grown on similar farms, only in the open sea. They are valued more than freshwater ones. Usually no more than one, less often three, pearls are extracted from one pearl shell. As a rule, pearls have a fairly regular shape and good shine. What is the reason why such pearls are more expensive? Salty sea water gives pearls a special shade and a slightly more even color than fresh water, which is why it is valued higher.

The growth rate of sea pearls is higher than the growth rate of river pearls. The lifespan of a sea pearl shell is no more than 8-10 years. In the open sea it is very difficult to protect shellfish from storms and changes in water temperature. When the temperature changes by just 2 degrees, the mollusk’s body begins to produce a weak acid, which instantly corrodes the top layer of the pearl – it, of course, becomes cloudy and completely loses its shine. Thus, pearl farmers often lose the result of many years of work in just one day. Therefore, to reduce the time of pearl production, most marine farms these days use a seed core.

Types of saltwater cultured pearls:

  • Cultured Akoya pearls are grown in the seas of southern Japan. The best harvest of Akoya pearls is harvested in late autumn – early winter. At this time, the pearl acquires its best shine. Akoya pearls reach 9 millimeters in diameter and are expensive. The price of pearls begins to rise rapidly with every millimeter if their diameter exceeds 8 millimeters. Akoya pearls are cultivated mainly in Japan, but now China is also exporting them.

Akoya pearls are grown in bivalves belonging to the genus Pinctada, whose Japanese name is Akoya-kai. This is where the name of this pearl comes from.

These mollusks reach a size of 7-8 cm, the size of their pearls is from 6 to 8 mm. Pearls of larger sizes are much less common. Most of the pearls produced are harvested on the islands of Honshu and Kyushu. The most famous and one of the oldest places for pearl cultivation is Ago Bay.

The growing process itself usually lasts 1,5-4 years.

Akoya pearls with quality characteristics are called Hanadama (“flower pearl”) and are classified as AAA and AA. Class A and B pearls make up approximately 30-40% of the total.

Akoya pearls range in size from 6-8 mm, rarely reaching 9-10 mm.

Akoya’s primary colors are pearlescent white, light cream and pearlescent pink. Sometimes there are pearls of silver and silver-greenish shades.

The shape of pearls may vary. A spherical shape is considered ideal.

  • South Sea pearls (Australian pearls). Rare, expensive and occupies an elite niche in the market. Australia and Indonesia produce white and golden pearls. Although the cultivation process is almost the same as for Akoya pearls, South Sea pearls are much larger, with pearl sizes reaching 6-20 mm.

South Sea pearls are a variety of cultured pearls grown using the Pinctada maxima mollusk. Currently cultivated along the coasts of the Pacific and Indian oceans, mainly in Australia, the Philippines, Indonesia and Myanmar.

South Sea pearls are the largest commercial type of cultured pearl. The average size of a South Sea pearl is 13mm. The bulk of the harvested pearls varies in the range from 9 to 20 mm. Such a large size of pearls is ensured by several factors:

The Pinctada maxima oyster can reach up to 30 cm across as an adult, allowing for a larger nucleus to be implanted into the gonads than, for example, Akoya oysters.

Shellfish of the Pinctada maxima species are distributed along the coasts between Australia and South China. Warm, clean water and excess plankton allow pearls to grow faster and speed up the metabolic processes inside the oysters.

Pinctada maxima pearl oysters are grafted when they are at least 24 months old, and it takes another 2 to 3 years to grow a pearl. A long cultivation period makes it possible to obtain elite pearls of such a large size.

South Sea pearls are distinguished by their large size, matte satin luster and warm shades of color. Basically, farms use two varieties of Pinctada maxima: the so-called silver-lipped and gold-lipped, that is, pearl oysters with silver and gold nacre, which determines the color of the pearl itself. From them they produce white pearls of pure color or with a silver overtone, and golden pearls.

A unique property of this pearl is its unusually thick layer of nacre, from 2 – 6 mm (for comparison, the thickness of the nacre of cultured Akoya pearls is only 0,35 – 1,2 mm).

In the commercial and industrial environment on the world market, the Black Pearls of Tahiti, and sometimes also the Pearls of Cortez, are sometimes classified as South Sea pearls. However, according to the classification of the International Jewelry Confederation CIBJO, adopted by the Gemological Institute of America GIA, the term South Sea Pearl refers only to pearls grown in Pinctada maxima pearl oysters.

In addition, the structure and density of the nacre shell of Australian pearls is better than that of Japanese pearls.

  • Tahitian pearls or black pearls. Each black pearl is a beautiful work of nature. None of them ever repeat in form. Black pearls are perfection itself. It does not need any special processing or to be given any special shape. Any – round, pear-shaped, “button” – it is extremely valuable, since it does not require any chemical treatment, since the pearls are extracted from the oyster already quite clean, dry and smooth. However, not all black pearls in jewelry stores are truly black. Sometimes craftsmen specially paint white pearls to create a special effect. But it is still a fake, albeit of high quality. The most natural black pearls of the highest standard are born in Tahiti. This pearl is distinguished by its ability to shimmer brightly in sunlight, as well as its unusual “metallic” color, which is not typical for other varieties of sea pearls. It is believed that Tahitian pearls are most often “black”, which is why its second name “black pearls” appeared, although in fact they are gray with more or less light shades. In addition, there are pearls of this variety with completely atypical colors: for example, blue (paecock), eggplant (eggplant), green, olive (olive green), blue and even red (magenta). The most valuable, and therefore the most expensive, are iridescent blue and cobalt blue colors. Each pearl in a Tahitian pearl necklace must have only a round shape, and also be at least 12 mm in diameter and, of course, ideally match the color of its neighbors on the string. Such a necklace sometimes costs a fortune. Because it takes years to collect. After all, not every master is lucky enough to create such a miracle. Nature creates too few perfect black pearls. Sometimes two similar black balls are not enough for earrings.

Black pearls always come first. It is his unique individuality that makes the master base his creative decisions on the dark, hot, magical pearlescent radiance. And, naturally, products made from black pearls are always extravagant. They are able to make a woman bright, unique, and memorable. Yes, black pearls for every woman are a witch’s drink, eternal renewal, the search for oneself, the eternal exploration of the unknown depths of one’s own personality, the discovery of a mysterious desert island in the ocean of one’s soul.

Beautiful pearls are not only found in the sea. Some freshwater mollusks also have the ability to create pearlescent beads inside their shells. Freshwater pearls look like those that were caught in the sea. And the process of its formation itself is almost exactly the same.

It creates equally impressive decorations:

  • Rings.
  • Earrings.
  • Graceful bracelets.
  • Luxurious necklaces, necklaces and beads.
  • Pendants and much more.

Up to 16 freshwater pearls can be found in one shell.

It is clear that wild pearls are collected in rivers where oysters live. And to obtain cultured material, special farms are created where oysters are grown, and foreign bodies are artificially placed in their shells, around which the mollusks begin to form pearls.

It is almost impossible to distinguish wild river pearls from cultured ones externally. Only very experienced practitioners can detect subtle differences between samples.

The appearance of each pearl is unique. Mollusks cannot create identical specimens, so real pearls are always unique.

The characteristics of each bead depend on the age of the mollusk, its stage of development, conditions, water composition and other factors. Under their influence, an element of one shape or another is formed, from an almost ideal sphere to an uneven irregular figure.

It is impossible to manage or control this process, because here the first violin belongs to the forces of nature. Therefore, even on special farms it is impossible to achieve a perfect spherical shape of pearls. Each of them has its own unique differences.

Differences between freshwater and sea pearls

To find out how to distinguish sea pearls from river pearls, you need to know the main characteristics when assessing the quality of this material:

  • Gloss level. River specimens are not as bright as those created in sea water. Their shine is not so noticeable, it is softer, more restrained, more subdued. If you place a sea pearl and a river pearl side by side, you will notice that the second one is duller.
  • Form. In any type of pearl you can observe the most whimsical and varied shapes of beads. But predominantly sea pearls are closer to a spherical shape, while freshwater pearls are more often oval and elongated.
  • Price. The cost of one river pearl is lower than the price of one sea specimen. This is primarily due to the fact that only one pearl is formed in sea shells, and about a dozen in river shells. Accordingly, the cost of cultivating freshwater pearls is significantly lower, which determines the affordable cost of each pearl. But when pricing, the quality of each copy is also taken into account.
  • Abrasion resistance. The layer of mother-of-pearl on marine specimens is usually thinner than on river specimens. Therefore, pearls from the sea lose their shine faster, as the thin nacre layer wears off. And river pearls remain shiny for many years.
  • Hue. In fresh waters, mainly milky pearls are formed. It is impossible to get black or pink pearls from rivers. But sea mollusks successfully cope with the task of creating pearls of a wide variety of shades.

As you can see, freshwater pearls have their own advantages. Therefore, it is a good choice to purchase. It is affordable, beautiful, durable. You will feel no less pleasant in jewelry with river pearls than in jewelry with sea pearls.

Varieties of freshwater pearls

The varieties of natural pearls obtained from river oyster shells are determined by the method of their extraction:

  • Natural or wild. It results from the completely accidental penetration of a foreign particle, such as a grain of sand, into the shell. The mollusk, trying to protect its internal space, begins to create layers of nacre around the foreign body. Over time, there are more and more layers, and a grain of sand turns into a pearl. Then the shell falls into the hands of a person, he opens it and discovers about a dozen beautiful beads that the diligent mollusk has been creating for years. Determining exactly where the oysters that create pearls are found is not easy. Typically, mining is carried out in places where large colonies of these creatures live. This is quite painstaking, time-consuming and costly work, which is why catching wild freshwater pearls is often considered unprofitable. It is carried out on a very modest scale.
  • Cultured freshwater pearls. This product is created on special farms and is a key way to obtain freshwater pearls. The essence of the technique used is that foreign particles are deliberately placed into the sink, and then the process is carried out in the same way as in natural conditions. The mollusk begins to work, building up pearlescent layers on the particle. As a result of his work, after a few years, the owner of the farm will receive ten or more pearls, depending on how many foreign fragments were placed in the shell.

All other types are not natural pearls, but their imitations.

Mining freshwater pearls

Freshwater pearl farms operate all over the world. China is the leader in this area, although centuries ago in deep Russian rivers people found wild pearls in sufficient quantities to embroider sundresses and hats with them.

You can try to find a pearl-bearing shell now. But we must understand that this matter will require effort and time. It is important to choose oysters from the very bottom of a fresh reservoir.

There are several parameters that will allow you to calculate the shell hiding the pearl:

  • Deformed doors;
  • Defects, chips and other signs of damage;
  • Lumpy shell surface.

The shell must be opened to find out for sure whether there is a pearl in it.

Variety of freshwater pearls

The cultivation process produces beads that are closest in shape to a regular sphere. But achieving a perfect ball is almost impossible. The most common types of freshwater pearl shapes are:

  • Circle;
  • Button;
  • Pear-shaped;
  • Baroque form;
  • Oval;
  • A drop.

Each of the forms is beautiful in its own way. When choosing a product, make sure that all the pearls are of the same shape. This is one of the indicators of the quality of decoration.

If we consider the color richness, then freshwater pearls have almost nothing to boast of, especially in comparison with sea pearls. The color of mother-of-pearl is determined by the type of oyster and the conditions in which it functions.

In addition to milky shades, freshwater pearls can be gray, brownish, beige and greenish.

Freshwater pearls can also be classified according to their size:

  • Large, varietal. Has a diameter of 5-10 mm. The most expensive because it takes a lot of time to grow such a specimen. It is used in jewelry more often than all other types.
  • Beads. Has a diameter of 3-5 mm. It takes about a couple of years to obtain such a copy. Also widely used in the creation of jewelry.
  • Dust. Has a diameter of up to 3 mm. Used for embroidering exclusive clothing. These pearls also vary in price. It depends on the method of production, size, shape, shade. Expensive wild specimens have a diameter of 10 mm. Their cost is about $400 apiece.

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