When we are thinking of pearls, often they think of the white, perfectly spherical white beads that are often worn strung as a necklace, bracelet, or as stud earrings. Most people don’t realize that there are, in fact, several different types of pearls. To be an informed consumer, there are certain things that are important to know about pearls.
How are pearls made:
Pearls are formed when a small foreign object or irritant finds its way into an oyster, mussel, or clam. These shelled creatures recognize that there is an irritant and responds by producing a calcium carbonate secretion as a way of protecting itself from this foreign object, which may be a small piece of sand or a food particle. This calcium carbonate protective coating protects the animal and reduces irritation. This protective coating is called nacre and it is what gives the pearl its iridescent white luster.
The most valuable pearls occur spontaneously in the wild, but are extremely rare. These wild pearls are referred to as natural pearls. Cultured or farmed pearls from pearl oysters and freshwater mussels make up the majority of those currently sold. Imitation pearls are also widely sold in inexpensive jewelry, but the quality of their iridescence is usually very poor and is easily distinguished from that of genuine pearls. Pearls have been harvested and cultivated primarily for use in jewelry, but in the past were also used to adorn clothing. They have also been crushed and used in cosmetics, medicines and paint formulations.
Whether wild or cultured, gem-quality pearls are almost always nacreous and iridescent, like the interior of the shell that produces them. However, almost all species of shelled mollusks are capable of producing pearls (technically “calcareous concretions”) of lesser shine or less spherical shape. Freshwater and saltwater pearls may sometimes look quite similar, but they come from different sources.
How long does it take for a pearl to be produced:
The process of producing a pearl can range from 6 months to several years. Even before this, it takes about 3 years for the mollusk to reach a mature age in order to produce a pearl. A mollusk is only able to begin the pearl making process naturally or with the help of humans when it reaches this mature age. Once the process begins, it can take anywhere up to 3 or 4 years for the pearl to reach its optimum size and thickness. This process requires a great deal of patience since it takes an extraordinary amount of time, money, and skill. When the pearl has reached its optimum, the pearl cultivator must carefully extract it from the mollusk. Then, he/she evaluates the pearl for its quality and determines whether or not it is qualified to sell on the market. Most mollusks that produce quality pearls are capable of producing up to 3 pearls in its lifetime. The average cultivated oyster usually costs the pearl farmer about $100 each, whether or not the pearl is gem-quality or not. This is a huge gamble, considering only about 3% of the pearls cultivated are sufficient quality to sell to jewelers. Pearls are formed inside the shell of certain mollusks as a defense mechanism against a potentially threatening irritant such as a parasite inside the shell, or an attack from outside that injures the mantle tissue. The mollusk creates a pearl sac to seal off the irritation. Pearls are thus the result of an immune response analogous in the human body to the capture of an antigen by a phagocyte.
The mollusk’s mantle (protective membrane) deposits layers of calcium carbonate (CaCO3) in the form of the mineral aragonite or a mixture of aragonite and calcite (polymorphs with the same chemical formula, but different crystal structures) held together by an organic horn-like compound called conchiolin. The combination of aragonite and conchiolin is called nacre, which makes up mother-of-pearl. The commonly held belief that a grain of sand acts as the irritant is in fact rarely the case. Typical stimuli include organic material, parasites, or even damage that displaces mantle tissue to another part of the mollusk’s body. These small particles or organisms gain entry when the shell valves are open for feeding or respiration. In cultured pearls, the irritant is typically an introduced piece of the mantle epithelium, with or without a spherical bead (beaded or beadless cultured pearls
Natural pearls:
Natural pearls are nearly 100% calcium carbonate and conchiolin. It is thought that natural pearls form under a set of accidental conditions when a microscopic intruder or parasite enters a bivalve mollusk and settles inside the shell. The mollusk, irritated by the intruder, forms a pearl sac of external mantle tissue cells and secretes the calcium carbonate and conchiolin to cover the irritant. This secretion process is repeated many times, thus producing a pearl. Natural pearls come in many shapes, with perfectly round ones being comparatively rare.
Typically, the build-up of a natural pearl consists of a brown central zone formed by columnar calcium carbonate (usually calcite, sometimes columnar aragonite) and a yellowish to white outer zone consisting of nacre (tabular aragonite). In a pearl cross-section such as the diagram, these two different materials can be seen. The presence of columnar calcium carbonate rich in organic material indicates juvenile mantle tissue that formed during the early stage of pearl development. Displaced living cells with a well-defined task may continue to perform their function in their new location, often resulting in a cyst. Such displacement may occur via an injury. The fragile rim of the shell is exposed and is prone to damage and injury. Crabs, other predators and parasites such as worm larvae may produce traumatic attacks and cause injuries in which some external mantle tissue cells are disconnected from their layer. Embedded in the conjunctive tissue of the mantle, these cells may survive and form a small pocket in which they continue to secrete calcium carbonate, their natural product. The pocket is called a pearl sac, and grows with time by cell division. The juvenile mantle tissue cells, according to their stage of growth, secrete columnar calcium carbonate from pearl sac’s inner surface. In time, the pearl sac’s external mantle cells proceed to the formation of tabular aragonite. When the transition to nacre secretion occurs, the brown pebble becomes covered with a nacreous coating. During this process, the pearl sac seems to travel into the shell; however, the sac actually stays in its original relative position the mantle tissue while the shell itself grows. After a couple of years, a pearl forms and the shell may be found by a lucky pearl fisher.
Cultured pearls:
Cultured pearls are the response of the shell to a tissue implant. A tiny piece of mantle tissue (called a graft) from a donor shell is transplanted into a recipient shell, causing a pearl sac to form into which the tissue precipitates calcium carbonate. There are a number of methods for producing cultured pearls: using freshwater or seawater shells, transplanting the graft into the mantle or into the gonad, and adding a spherical bead as a nucleus. Most saltwater cultured pearls are grown with beads. Trade names of cultured pearls are Akoya, white or golden South sea, and black Tahitian. Most beadless cultured pearls are mantle-grown in freshwater shells in China, and are known as freshwater cultured pearls.
Cultured pearls can be distinguished from natural pearls by X-ray examination. Nucleated cultured pearls are often ‘preformed’ as they tend to follow the shape of the implanted shell bead nucleus. After a bead is inserted into the oyster, it secretes a few layers of nacre around the bead; the resulting cultured pearl can then be harvested in as few as twelve to eighteen months.
When a cultured pearl with a bead nucleus is X-rayed, it reveals a different structure to that of a natural pearl (see diagram). A beaded cultured pearl shows a solid center with no concentric growth rings, whereas a natural pearl shows a series of concentric growth rings. A beadless cultured pearl (whether of freshwater or saltwater origin) may show growth rings, but also a complex central cavity, witness of the first precipitation of the young pearl sac.
What does it mean for a pearl to be “cultured” :
The term “cultured” refers to the process by which the pearl is made. As previously described, a pearl is formed by the invasion of a irritant within an oyster, mussel, or clam. When pearls are “cultured”, it means that this process is initiated by the help of humans in which the ‘seed’ or ‘nuclei’ is surgically introduced within the mantle of the mollusk. For freshwater pearls, a nuclei is not required to initiate the pearl making process. Instead, a small cut to the soft tissue of the mollusk is sufficient to initiate the secretion of the nacre, starting the pearl forming process. Freshwater pearls form in various species of freshwater mussels, family Unionidae, which live in lakes, rivers, ponds and other bodies of fresh water. These freshwater pearl mussels occur not only in hotter climates, but also in colder more temperate areas such as Scotland (where they are protected under law). Most freshwater cultured pearls sold today come from China.
saltwater pearls, a nucleated bead made up of natural mother-of-pearl and a small piece of mantle tissue is introduced into the belly of the oyster. This bead forms the nucleus of the pearl from which the layers of natural nacre are layered upon. Unlike cultured pearls, natural pearls are pearls that have been organically formed in nature — without the aid of humans. These pearls are extremely rare and only a select few still are on the market. They tend to be heavier, denser, and more lustrous than their cultured counterpart. Saltwater pearls grow within pearl oysters, family Pteriidae, which live in oceans. Saltwater pearl oysters are usually cultivated in protected lagoons or volcanic atolls.
How can you tell if a pearl is real or fake :
How can you tell if a pearl is real or fake? Fake pearls are, generally, glass beads that have been coated. While they might have some luster, the luster of fake pearls lacks the depth seen in quality real pearls. . Also, since real pearls are organically made, rarely are perfect round and flawless, unless they are very high quality. If the pearls all look perfectly identical and flawless, and lack their own uniqueness or “personality”, this is one indication they may be fake. Since real pearls have many layers of natural nacre, they are almost always cool to the touch. If you rub a suspicious pearl and it feels somewhat warm, this is most likely a fake since it suggests there is a glass or plastic bead under the coating which is absorbing the heat. Another give-away is the weight of the pearl. A real pearl would feel dense and heavier compared to a fake pearl which is simply a bead. Finally, the “tooth test” is a tried-and-true method to determine the authenticity of a pearl. For the “tooth test” you take the pearl and rub it against one of your teeth. If it feels smooth as you rub it, it is most likely a fake. If it feels grainy, it is a real pearl. This is because a real pearl’s nacre has microcrystalline structures which would cause friction against a tooth. A fake pearl would not have this characteristic and would be smooth against your tooth.
What determines the value of a pearl :
1.) How/where it is produced
As previously mentioned, natural pearls are the most rare and most expensive, being that only a select few remain on the market. With that being said, most pearls on the market are the product of an organic and natural process with the help and aid of humans, which is referred to as pearl cultivation or harvesting. Also, saltwater pearls tend to be more valuable than freshwater pearls.
2.) Nacre
The quality the nacre is a major factor which contributes to the assessed value of the pearl. Nacre thickness refers to the amount of nacre that surrounds the nucleus of the pearl. Pearls which have a greater nacre thickness are considered more valuable than pearls that have a lower nacre thickness. One reason for this is because nacre thickness indicates how long it took to produce the pearl, since each layer is added organically by the mother mollusk. The older the pearl, the greater the nacre thickness, and the greater the value. Determining nacre thickness takes experience and skill. An informed consumer can tell the difference by evaluating the luster and weight of the pearls. Pearls that have brilliant luster tend to be the result of greater nacre thickness, since the nacre is what causes the luster. They also tend to be heavier since the nacre adds weight to the pearl.
3.) Surface
When buying pearls, it is also important to scrutinize the surface of the pearl for marks, bumps, or other imperfections. Since pearls are the result of a natural process, they will rarely ever be perfect and sometimes, even, the imperfections can add to the uniqueness of the pearl. However, if buying a strand of pearls, some imperfections lower the value of the pearls since it might draw unwanted attention away from the rest of the pearls.
4.) Shape
In general, the rounder the pearl, the higher the value. Some pearls, such as baroque pearls, are valued for their organic shape. However, pearls such as these are still generally not as expensive as pearls of same weight and luster that are round.
5.) Color
The most common colors of pearls exist between pale shades of white, champagne, rose, silver, and sometimes green. Tahitian pearls are the only pearls that nare naturally black. Natural colors can come in various shades and hues of these colors. When selecting your pearls, it is also important to know if the color of the pearls are natural or color treated. Color treating pearls is a common practice, and therefore, can create pearls of nearly any color. Since this is an artificial process, it is important to know if the pearls you are buying are natural or color treated, as color treated pearls are typically less expensive. In choosing your pearls, preferred tones are based on individual tastes and preferences. In general, rose colored overtones are most flattering for those with pale skin. Cream and golden hued pearls are most flattering for those with tanned and darker complexions.
6.) Size
If all the other factors are the same, the final factor that should be assessed is the size. Pearls are measured in millimeters and a single millimeter difference can substantially increase increase its value.
What is the difference between freshwater and saltwater (Akoya, Tahitian, South Sea) pearls :
The most obvious difference between freshwater and saltwater pearls are the environments in which they are produced. Freshwater pearls are derived from mollusks in freshwater environments, while saltwater pearls come from saltwater sources.
What are freshwater pearls :
Freshwater pearls are produced my mussels and are commonly found in lakes and rivers in China. Originally, freshwater pearls were found to be more irregular in shape and less lustrous, however, due to advances in technology, the quality of freshwater pearls has improved remarkably in their range in color, shape, luster, and quality. Today’s freshwater pearls are sometimes likened to Akoya pearls, which are expensive saltwater pearls. Freshwater pearls serve as a less expensive option to Akoya pearls, which are approximately five times more expensive. However, unlike Akoya pearls, freshwater pearls are generally smaller, more irregular in shape, and often not well matched on a strand.
What are saltwater pearls :
Generally, pearls that come from saltwater environments are rounder and exhibit greater luster than their freshwater counterpart. In addition, the saltwater pearl industry is much smaller and the cost of production is significantly more expensive, making these pearls more treasured and valued.
What are the different types of saltwater pearls:
1.) Akoya: Akoya pearls are saltwater cultured pearls found in the salt waters of Japan and are grown in pinctada fucata, or Akoya pearl oysters. They are the iconic “classic white pearls”, known for their glossy white, rosy, and silver white color and luster. They are distinguished by their perfectly round shape and are generally larger and more lustrous than freshwater pearls. Compared to freshwater oysters, akoya pearl oysters rarely produce any more than 2 pearls in their lifetime.
2.) Tahitian: Tahitian pearls are the only naturally occurring black pearls in the world. These pearls are created by the black-lipped pinctada margaritifera oysters found in the waters of French Polynesia. They are considered the second most valuable pearls in the world, typically treasured for their exotic colors and extraordinary luster, caused in part by their unique nacre thickness. By French Polynesian law, the minimum nacre thickness allowed for the export of Tahitian pearls is 0.8mm, which is considered quite thick in the pearl and jewelry industry. While Tahitian pearls are often characterized by their iconic black color, they are actually the pearls with the greatest variation of exotic colors. Some examples are peacock green, silver green, blue, and eggplant.
3.) White and Golden South Sea: Considered the world’s most rare and valuable pearls, these pearls range from pure white to deep golden tones and have the thickest nacre of all cultivated pearls. Their luster is unlike any other due to the aragonite platelets that exist within the nacre. These pearls take nearly two times as long to cultivate as the Akoya pearls and the unique type of pearl oysters that produce these pearls are delicate and sensitive. Therefore, production is extremely limited since they can only survive in the waters off the northwest coast of Australia.
What does baroque mean?
Baroque pearls are pearls of irregular shape, valued for their organic nature. No two baroque pearls are alike, adding to their intrinsic value, and serve as an intriguing conversation piece. Large baroque pearls are even more valuable, as they can take up to 2 years to form.
What is Mother of pearl :
Mother of Pearl refers to the coating of nacre found within the inside part of the mollusk shell. The inside part of the shell reflects the iridescent luster and qualities that characterize pearls themselves.
What are keshi pearls:
Keshi pearls are known for their unique, organic, abstract shapes and gorgeous luster. Keshis are all natural pearls because there is no nucleus inside – meaning the keshi pearl is nothing but pure nacre. The keshi pearl forms as a by-product of cultivation. Because nacre is precious material, keshi pearls are highly prized, being made up of nothing but pure nacre. For this reason, they are sold by weight like gemstones. All natural keshi pearls are unique treasures of rare and precious material.