The Pearl

Pearl, a fine gemstone

Pearls are what are known as "organic gems" because they are produced by animals (bivalve molluscs, to be precise) rather than by geological phenomena. Furthermore, a distinction is made between natural pearls, also known as fine pearls, and cultured pearls, which come from oyster farming.

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

What is the origin of the name "pearl"?

While the etymology of the word “pearl” may have been attributed to the Latin sphaerula, “small sphere,” due to their spherical shape, or to the Latin perna, “shellfish,” which referred to a variety of mollusk that produces them, the origin of the name “pearl” comes from the Roman legions’ slang pira or pirla, a term used to mock the “little pears” hanging from the ears of matrons of the time.

Pearls can also have a geographical origin included in their name, such as Tahitian pearls (traditionally known for being black and with an overtone) or Akoya pearls from Japan (white and cream).

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

Pearls are formed in bivalve mollusks (with two shells) following the introduction of a foreign body (e.g., grains of sand) inside the shells. This element, irritating for the mollusk, triggers a bodily mechanism in the animal that aims to cover the cause of the discomfort with nacre. Thus, the mollusk covers the disturbing nucleus with multiple concentric layers of nacre to minimize the irritation produced by its presence.

Why can pearls have different shapes?

Since pearls are formed by layers of nacre around an irritant core within the mollusc's body, their shape is more or less round.
However, the final shape of the pearl can vary depending on certain factors such as the environment of the mollusc that secretes it, the shape of the element introduced into the shell, and the location of the foreign body's graft.
Indeed, the definitive shape of the pearl depends on the location of the original foreign body within the oyster: if it is free within the mollusc, the pearl will likely be round. If the foreign body is attached to or near the inner wall of the shell, its shape will be irregular.

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

Spherical (round and semi-round)Symmetrical (buttons, ovals, drops or pears, barrels, circled)Baroque, which are pearls with abstract shapes (semi-baroque, baroque, "very baroque")Others (Keishi, Mabé, Blister pearl)

How are pearl size and weight expressed?

In the jewellery industry, it is more common to distinguish pearls by their diameter. This is then expressed in millimetres.

However, it is also possible to weigh pearls using three units of measurement:

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

Why can pearls be different colors?

Pearl colors 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 mollusk's environment: 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 visible by transparency through the mother-of-pearl.

Thus, nine easily distinguishable pearl shades can be identified: white, pink, cream, rosy cream, gold, green, blue, grey, and black.
But it is also possible to observe sub-shades: grey, green, brown, blue, yellow, and pink, which gives them a particular personality.

Features

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

Orient is the beautiful optical effect a pearl can possess. This is the iridescent and shimmering "rainbow" glow that seems to move when the pearl is turned. Luster is the reflection of light on the pearl. The greater 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 surface imperfections (link to the next point), and a good nacre thickness (link to the point after that). The Surface of the pearl

It is possible for the pearl's surface to have imperfections such as holes, roughness, scratches, or spots.
While some can be eliminated or altered during drilling or setting, the most sought-after pearls, and therefore the most expensive, are pearls with no surface imperfections.
Indeed, the fewer imperfections a pearl has, the greater its luster will be because light will reflect uniformly across its entire surface.

Nacre thickness.

The greater the nacre thickness, the longer the cultivation time and the larger the pearl will be (for an equivalent nucleus).
Furthermore, a thick layer of nacre reduces the possibility of seeing the graft through it, thus unifying its color and allowing for greater luster. Indeed, nacre is inherently slightly transparent and only reflects light well beyond a certain thickness.
Finally, the more nacre accumulated, the "stronger" the pearl will be (it is important to remember here that a pearl remains fragile and should be handled with care).
This is why a pearl with a thick nacre layer will be more expensive than a pearl with a thinner nacre thickness.

What is the difference between natural and cultured pearls?

Pearls are the result of an irritating micronucleus that slips inside a bivalve mollusc, which then covers it with nacre to soften it.
This phenomenon is relatively rare, and it is difficult to find the small percentage of molluscs that develop them naturally, which is why natural pearls, also known as fine pearls, are so rare.
To counteract this unpredictable variable, humans began cultivating pearl-producing molluscs. Thus, they interfere not only with the location of the pearl oysters but also with the pearl development process, as they themselves induce the irritating element between the two shells, thereby guaranteeing the production of a pearl. This introduced nucleus or graft is called a "seed" because it initiates the pearl process.

What are the different types of pearl farming? Today, cultured pearls represent the vast majority of the market, and there are two main types of farming:

  • Saltwater pearls

    These pearls mainly come from Japan, China, the Polynesian Coasts, and the Australian Coasts.
    The molluscs are generally placed in plastic baskets or cages submerged 2 to 6 meters deep.
    The larger the grafted nucleus, the older the mollusc must be for the graft to take properly. However, the average age of the mollusc during an initiation is three years. This is followed by three to four years of cultivation during which the mollusc remains submerged. At this stage, the nacre thickness is about 0.8 to 1.2 millimeters. After 7 years, the oyster no longer produces nacre.

  • Freshwater pearls.

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

    This type of cultivation produces excellent results in terms of roundness and quality. Furthermore, it offers a color palette reminiscent of antique natural pearls: pinkish-white, orange, golden-yellow, pinkish-purple, blue, brown, and more.

**What are the main varieties of cultured pearls?**

  • AKOYA pearls

    These pearls primarily originate from China, Korea, and Japan.
    Their dominant color is creamy white with pink or green overtones.
    The cultivation time is 1 to 2 years for pearls ranging from 2.5 to 10.5 millimeters in diameter. Their shapes are most commonly round, semi-round, or baroque. Beyond 9 mm, they are considered very rare.

  • SOUTH SEA white pearls

    These pearls primarily originate from Australia, Indonesia, the Philippines, and Burma, and are white in color with silver, pink, or golden overtones; white pearls with no color nuances are the most prized in the current pearl market.

    The cultivation period 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 in shape. Beyond 17 mm, they are considered very rare.

  • SOUTH SEA dark pearls

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

    As a result, several commercial names have been attributed to them to approximately classify the different shades of South Sea pearls:

    Silver: gray with silver reflectionsMoon: pale grayAubergine: dark gray with a red huePistachio: gray with a green hueLime blossom: light gray with a green huePeacock: black with a green huePigeon: gray with a violet hueCherry: black with a violet hueChampagne: gray with a yellow hueLavender: black with a bluish hueTahiti gold: black with golden reflections

    The cultivation time is approximately 18 months.

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

  • FRESHWATER pearls

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

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

    The cultivation period is 1 to 5 years for pearls 2 to 10 millimeters in diameter, and up to 14 mm for the rarest pearls. Their shapes are also very varied: round, semi-round, baroque, button, pear, stick, cross... 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 pearl-set piece of jewelry created?

Once the cultivation period is over, pearl farmers "harvest" and extract cultured pearls from mollusks, then rinse them with water and dry them on the farm.


This is followed by a step to remove impurities from the pearls. To do this, the pearls are placed in a drum to which bamboo shavings and liquid wax are added. It is at this stage that the luster of the pearls appears.

 
It is then possible to bleach or dye some cultured pearls to improve their color, but this practice greatly devalues them.


Once the pearls are collected and polished, they are sorted by size, shape, color, and quality, then pairings are chosen to decide which pearls will form earrings, necklaces, rings, etc.


As for pearls intended for stringing, for necklaces or bracelets for example, they are not only chosen harmoniously but are also drilled.
Indeed, for the final jewelry to be harmonious, the pearls must resemble each other as much as possible. This is why matched cultured pearls are drilled and then immediately strung on a strand to keep the pearls together.

Then comes the drilling step: delicate and essential because it is definitive. Drilling can enhance certain pearls, either by highlighting a shape or by making a small defect disappear, which is then replaced by the hole.
Finally, if the definitive piece of jewelry is a ring or a piece of jewelry that does not require stringing, the cultured pearl is only drilled on one side and then glued onto a metal rod. The jewelry is then said to be set with a cultured pearl.

**How to assess the quality of pearls?**

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

There are two systems for evaluating pearl quality: the AAA-A and the A-D, also known as the "Tahitian system."

  • THE AAA-A SYSTEM

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

    AA+: The pearl has a very good luster and its minor flaws do not exceed 15% of its total surface; a small deep imperfection on the surface is tolerated. AA: The pearl has a very good luster and its minor flaws do not exceed 25% of its total surface; a small deep imperfection on the surface is tolerated. A+: The pearl has an average luster and its minor flaws do not exceed 40% of its total surface; its deep imperfections must not exceed 10% of its surface. A: The pearl has a weak luster and its flaws do not exceed 60% of its total surface; its deep imperfections must not exceed 20% of its surface.

  • **THE A-D SYSTEM or TAHITI system**

    Used by the Polynesian Pearl Cultivation Services, this system evaluates pearls on a descending scale from A to D.

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

**What is the role of pearls in history?**

The oldest evidence of pearls dates back to 2,206 BC, as recorded by a Chinese historian.
Pearls were first discovered in Persia before being exported to the West by Alexander the Great.

It wasn't until the 13th century that a Chinese man named Ye-Jin-Jang made the first attempts at cultivation, discovering a way to artificially produce pearls by intentionally introducing small impurities into healthy shells.
The first successful pearl cultivation is attributed to the Japanese Kokichi Mikimoto in 1893.

Given the commercial success of cultured pearls and the rarity of natural pearls, cultured pearls quickly became democratized and now dominate the pearl market.
Most often associated with the moon, water, and women, pearls have been attributed all sorts of symbolism and powers throughout different eras and regions.
Eastern and Hindu civilizations thus ascribed aphrodisiac, fertilizing, and talismanic properties to them. It was also said to have a 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 Gnostics attributed great spiritual power to it.
Today, the pearl symbolizes sensitivity, grace, faith, humility, and love, as well as June births and the 30th wedding anniversary.

How to care for your pearls?

Pearls are fragile and can "age" over time. Indeed, a pearl's lifespan is estimated to be between 100 and 150 years before it becomes dull, cracks, and disintegrates.
It is possible to maintain the pearl's beauty by avoiding exposure to severe dryness and excessive humidity. In addition, acids, perspiration, cosmetics, perfumes, and hairspray can attack and damage it. As pearls scratch easily, care must also be taken to ensure they do not come into contact with other gemstones or metals, whether when worn or stored.

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