The pearl, fine stone

The Aqua Ondes earrings in white gold set with two Tahitian pearls marry the curves of the face to reveal a delicate femininity.

Pearls are what we call “organic stones” since they are produced by animals (bivalve molluscs to be precise) and not by geological phenomena. We also differentiate natural pearls, called fine, from cultured pearls that come from oyster farming.

What is the origin of the name "pearl"?

If the etymology of the word "pearl" could be attributed to the Latin sphaerula, "small sphere", because of their spherical shape or even to the Latin perna, "shell" which referred to a variety of mollusk which produces it, the The origin of the name “pearl” comes from the slang of the Roman legions pira or pirla, a term that was used to make fun of the “little pears” hanging from the ears of the matrons of the time.

Pearls can also have a geographical origin included in their name, such as Tahitian pearls (traditionally known to be black and with orient) or Akoya pearls in Japan (white and cream).

What are the shapes, sizes, colors and characteristics of the pearl?

Pearls are formed in bivalve molluscs (with two shells) following the introduction of a foreign body (example: grains of sand) inside the shells. This element, irritating for the mollusk, triggers a bodily mechanism of the animal which aims to cover the cause of the discomfort with mother-of-pearl. Thus, the mollusc covers the disturbing core with multiple concentric layers of nacre in order to minimize the irritation produced by its presence.

Why can the pearl be of different shapes?

Since the pearls are formed by layers of mother-of-pearl around an irritating core for the body of the mollusk, the shape of the pearls is more or less round.
However, it is possible, depending on certain factors such as the environment of the mollusk which secretes it, the shape of the element introduced into the shell as well as the location of the foreign body graft, that the final shape of the pearl varies .
Indeed, the final shape of the pearl depends on the location of the original foreign body in the oyster: if it is free in the mollusc, the pearl will probably be round. If the foreign body is attached or close to the inside wall of the shell, its shape will be irregular.

Thus, pearls can have different shapes grouped into three main categories, namely:

The spherical (round and semi-round) The symmetrical (buttons, oval, drop or pear, barrel, circled) The baroque which are pearls with abstract shapes (semi-baroque, baroque, "very baroque") The others (Keishi, Mabé, Pearl Blow)

How do you express the size and weight of the pearl?

In the world of jewelry, it is more common to distinguish pearls by their diameter. The latter is then expressed in millimeters.

On the other hand, it is also possible to weigh the pearls according to three units of measurement:

The Carat: Unit of weight for gems, 1 carat = 0.2 grams. The Grain: Unit of weight used in the fine stone trade (natural). 1 grain = 0.053 grams. Momme and Kan: Japanese units of weight traditionally used in the pearl trade. 1 momme = 3.75 grams

Why can the pearl be of different colors?

The colors of pearls are very varied and depend on three criteria:

The color of the mother-of-pearl secreted by the mollusk, which differs from one species to another.The environment of the mollusk: the pigments contained in the water, its depth and its salinity can influence the color of the mother-of-pearl. The color of the implant which can be seen by transparency through the mother-of-pearl.

Thus, we can identify nine easily discernible shades of pearls: white, pink, cream, cream pink, gold, green, blue, gray and black.
But it is also possible to observe sub-shades: gray, green, brown, blue, yellow and pink, which gives them a particular personality.


The value of a pearl is determined not only by its shape, size and color but also by four other variables: its orient, its luster, its surface and its thickness of nacre.

The orient is the beautiful optical effect that a pearl can have. This is the iridescent and shimmering luster of "rainbow" color which seems to move when the pearl is turned. Luster is the reflection of light on the pearl. The higher the luster, the higher the quality of the pearl, and the more expensive it will be. This reflection of light is facilitated by a homogeneous structure of the pearl, few defects on the surface (link to the next point) and a beautiful thickness of mother-of-pearl (link to the next point). The Surface of the pearl

It is possible that the surface of the pearl has defects such as holes, roughness, scratches or stains.
While it is possible to eliminate or alter some of them during drilling or crimping, the most sought-after pearls, and therefore the most expensive, are pearls without any surface defects.
Indeed, the less the pearl will have defects, the more its luster will be important because the light will be reflected in a homogeneous way on the whole of its surface.

The thickness of mother-of-pearl.

The greater the thickness of the mother-of-pearl, the longer the culture time and the larger the pearl will be (with an equivalent nucleus).
In addition, a large layer of pearl reduces the possibility of seeing the graft through, thus standardizing its color and allowing a greater luster. Indeed, mother-of-pearl is by nature slightly transparent and only reflects light well from a certain thickness.
Finally, the more mother-of-pearl there is accumulated, the more the pearl will be "solid" (it is important to remember here that a pearl remains fragile and that it must be handled with care).
This is why a pearl with a large nacre layer will be more expensive than a pearl with less nacre thickness.

What is the difference between fine pearls and cultured pearls?

The pearls result from an irritating micronucleus that slips inside a bivalve mollusc and which the latter covers with mother-of-pearl to soften it.
This phenomenon is relatively rare and it is difficult to find the small percentage of molluscs that develop it in their natural state, which is why natural pearls, also called fine, are so rare.
In order to deal with this unpredictable variable, man began to cultivate pearl-producing molluscs. Thus, it not only interferes on the locality of pearl molluscs but also on the pearl development process since it itself induces the irritating element between the two shells, thus guaranteeing the production of a pearl. This introduced nucleus or graft is called "primer" since it initiates the pearling process.

What are the different types of pearl culture?

Today, cultured pearls represent the vast majority of the market and two types of culture can be retained:

seawater pearls

These pearls come mainly from Japan, China, the coasts of Polynesia and the coasts of Australia.
The molluscs are generally placed in baskets or plastic cages immersed 2 to 6 meters deep.
The larger the grafted nucleus, the older the snail must be for the graft to take properly. However, the average age of the mollusk when primed is three years. Then follows three to four years of culture during which the mollusc remains immersed. At this stage, the thickness of the nacre is about 0.8 to 1.2 millimeters. After 7 years, the oyster no longer produces nacre.

Freshwater pearls.

Produced mainly in Japan, China, Scotland, Ireland, France, Austria, Germany and the United States (in the Mississippi), freshwater pearls are cultured at a depth of 1 to 2 meters depth and the molluscs that produce them have a lifespan of about 13 years.

This type of culture produces excellent results in terms of roundness and quality. In addition, it offers a color palette reminiscent of the fine pearls of yesteryear: white-pink, orange, yellow-gold, pink-violet, blue, brown...

The main varieties of cultured pearls are:

AKOYA pearlsLight SOUTH SEA pearlsDark SOUTH SEA pearlsFRESHWATER pearls

What are the main varieties of cultured pearls?

AKOYA pearls

These pearls come mainly from China, Korea and Japan.
Their dominant color which is creamy white with pink or green reflections.
The culture time is 1 to 2 years for pearls 2.5 to 10.5 millimeters in diameter. Their shapes are also generally round, semi-round or baroque. Beyond 9 mm, they are considered very rare.

The clear pearls of the SOUTH SEAS

These pearls come mainly from Australia, Indonesia, the Philippines and Burma and are white in color with silver, pink or gold reflections; white pearls with no shade of color are the most popular in today's pearl market.

The cultivation time is 18 to 24 months.

The pearls thus obtained measure between 9 to 20 millimeters in diameter and can be round, semi-round, button, pear, baroque or circled. Beyond 17 mm, they are considered very rare.

The dark pearls of the SOUTH SEAS

These pearls come from the region of Tahiti, the Tuamotu Archipelago, Gambiers and Cook Island and are predominantly gray in color. They sometimes have a reflection or a shade due to the iridescence of the pearl such as pink, green, yellow, red or more rarely blue.

This is how several trade names have been attributed to them in order to roughly classify the different shades of South Sea pearls:

Silver: gray with silver tintsMoon (moon): pale grayEggplant: dark gray with red tintPistachio: gray with green tintLinden: light gray with green tintPeacock: black with green tintPigeon: gray with purple tintCherry: black with purple tintChampagne: gray with yellow tintLavender: black with a bluish tintTahiti gold: black with golden reflections

The cultivation time of about 18 months.

The pearls thus obtained measure between 8 to 20 millimeters in diameter and can be round, semi-round, button, pear, baroque or circled. Beyond 16 mm, they are considered very rare.


These pearls come mainly from China or Japan and are white (the most popular), cream, purple or even orange.

Freshwater pearls, unlike other cultured pearls, are not formed from a solid nucleus but from a particular primer: a piece of epithelial tissue, also called "coat", taken from an oyster of the same species.

The culture time is 1 to 5 years for pearls of 2 to 10 millimeters in diameter, even up to 14 mm for the rarest pearls. Their shapes are also very varied: round, semi-round, baroque, buttons, pears, sticks, crosses, etc.

The pearls thus obtained can also be called "Biwa" pearls in reference to Lake Biwa or Biwako, in western Japan, where the first freshwater pearls were cultivated.

How is a jewel set with pearls created?

Once the culture period is over, the pearl farmers “harvest” and extract the cultured pearls from the molluscs, then rinse them with water and dry them on the farm.

Then follows a step aimed at removing the impurities from the pearls. To do this, the latter are placed in a drum to which are added bamboo shavings and liquid wax. It is at this stage that the luster of the pearls appears.

It is then possible to whiten or dye certain cultured pearls to improve their color, but this practice greatly devalues ​​their value.

Once the pearls have been collected and polished, they are sorted by size, shape, color and quality then the pairings are chosen in order to choose which pearls will form earrings, necklaces, rings...

Regarding the beads intended for threading, for necklaces or bracelets for example, they are not only chosen in a harmonious way but are also pierced.
Indeed, in order for the final jewelry to be harmonious, the pearls must resemble each other as much as possible. This is why matching cultured pearls are pierced and then immediately strung on a row to keep the pearls together.

Then follows the drilling stage: delicate and essential because it is final. Drilling can make it possible to enhance certain pearls, either by enhancing a shape, or by making a small defect disappear, then replaced by the hole.
Finally, if the final jewel is a ring or a jewel that does not require threading, the cultured pearl is pierced only on one side and then glued to a metal rod. The jewel is then said to be set with a cultured pearl.

How to assess the quality of pearls?

The quality and therefore the price of a pearl depends on 6 criteria: its shape, its size, its color, its luster, its surface and its thickness of mother-of-pearl. Additionally, a fine pearl is exponentially more expensive than a cultured pearl due to its rarity.

There are two systems for evaluating the quality of a pearl: the AAA-A and the AD, also called the “Tahiti system”.


Used by the GIA (Gemological Institute of America), this system serves as an international reference and rates pearls on a decreasing scale from AAA to A.

AA+: The pearl has a very beautiful luster and its slight defects do not exceed 15% of its total surface; a small deep imperfection on the surface is tolerated.AA: The pearl has a very beautiful luster and its slight defects do not exceed 25% of its total surface; a small deep imperfection on the surface is tolerated. A+: The pearl has a medium luster and its slight defects do not exceed 40% of its total surface; its deep imperfections must not exceed 10% of its surface. A: The pearl has a low luster and its defects do not exceed 60% of its total surface; its deep imperfections must not exceed 20% of its surface.


Used by the Pearl Culture Services of Polynesia, this system grades pearls on a decreasing scale from A to D.

A: Corresponds to the highest quality pearl with a high luster and very slight imperfections not exceeding 10% of the pearl's total surface area. B: The pearl has a high to medium luster and its imperfections are slight and do not exceed 30% of its total surface.C: The pearl has a medium luster and its imperfections are moderate and do not exceed 60% of its total surface.D: The pearl has a low luster and there are two cases in with regard to its imperfections: if they are rather slight, they can exceed 60% of the total surface; if they are quite large and deep, they should not exceed 50% of the total surface.

What is the pearl's place in history?

The oldest pearl testimony dates from 2,206 BC with the writings of a Chinese historian.
The pearl was first discovered in Persia before being exported to the West by Alexander the Great.

It was not until the 13th century and a Chinese named Ye-Jin-Jang for the first culture trials with the discovery of a way to artificially produce pearls by deliberately introducing small impurities into healthy shells.
The first successful pearl culture is attributed to the Japanese Kokichi Mikimoto in 1893.

Faced with the commercial success of cultured pearls and the scarcity of fine pearls, cultured pearls quickly democratized to dominate the pearl market today.
Most often associated with the moon, water and women, the pearl has been attributed all kinds of symbolism and powers over the ages and regions.
Eastern and Hindu civilizations thus lent it aphrodisiac, fertilizing and talismanic properties. She was further said to have an invigorating power, even after death; many pearls were thus found in the tombs of kings and nobles.
In Persia, the pearl had a noble and sacred character, hence its incorporation into royal ornaments.
Among the Greeks, the pearl was the emblem of love and marriage.
In Christian tradition, the pearl was associated with the spiritual birth of Christ in the baptism of fire and the Gnostics attribute great spiritual power to it.
Today, the pearl symbolizes sensitivity, grace, faith, humility and love as well as births in June and the 30th wedding anniversary.

How to take care of your pearls?

The pearl is fragile and can "age" over time. Indeed, the lifespan of a pearl is estimated between 100 and 150 years before it becomes dull, cracks and disintegrates.
It is possible to maintain the beauty of the pearl by avoiding exposure to severe droughts and excess humidity. In addition, acids, perspiration, cosmetics, perfumes or hairspray can attack and damage it. The pearls scratch easily, it is also necessary to be careful that they do not come into contact with other gems or metals, whether when they are worn or stored.

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