Where do pearls come from?

Olanrewaju Arilomo

Have you ever wondered about the origin of those attractive dangling neckpiece or pieces of jewellery you see on people that you admire? Pearls are loved and cherished but whoever stopped to ask the question “where do pearls come from?”

You can write your answer to the question ‘where do pearls from?” somewhere and find out if it correlates with what you are about to read soon. Let’s go on this pearly ride.

Ever heard of the word defence mechanism? It is that psychological concept humans (which they are often not aware of) use to protect themselves against internal conflict; denial, regression, displacement. It seems like it is not only humans that make use of this concept, mollusks (an invertebrate of a large phylum which includes snails, slugs, mussels and octopuses but in this case oysters and occasionally clams and mussels). In answering the question “where do pearls come from”, it is important to make the distinctions between natural pearls and cultured pearls. One is as a result of the oyster trying to naturally defend themselves against foreign bodies while the other is a result of the direct exploitation of this defence mechanism.

The natural pearls are not easy to come by, it is as a result of an intruder which could be sand grains, parasite, a threatening irritant, or as a result of attacks on the protective layer of the oyster’s organs which is called the mantle. These intruders gain passage when the shell valves are opened when they are feeding or during respiration. We know you are still wondering how all these are related to that beautiful neckpiece you have. Just have it in mind that we just started on this pearly ride and still want to get to the root of that question we asked earlier, “where do pearls come from?”

Remember the defence mechanism that we mentioned earlier, it is at this point it comes into play, the oyster which could be in either freshwater or saltwater environments then immediately adapts this method (defence mechanism) by quickly covering this intruder with various layers of nacre. This is getting complicated with the mention of nacre. Nacre is as a result of the amalgamation of aragonite and conchiolin. The protective layer which is the mantle leaves layers of calcium carbonate (CaCO3) which is in the form of the mineral aragonite that is held together by a natural horn-like compound called conchiolin. Back to the nacre, this forms the mother of pearl. Pearl then occurs as a result of the build-up of the mother-of-pearl on each other. Your pearl is finally coming to life. It is important to note that natural pearls come in various shapes, those round ones are rare.

For a detailed explanation to the question, “where do pearls come from?” there are few complicated things involved but will be simplified for understanding. The columnar calcium carbonate (rich in natural material that signifies a budding mantle tissue was formed in the early stage of pearl development) forms a central brown zone and a white (goes from yellow to white) exterior zone which the nacre is made of. Out of original location living cells may function in their new location which will most likely result in a cyst. This change from the original location might be a result of an injury which enables external mantle cells to be disconnected from the original layer. There is a chance of survival for this cell which enables them to form a small store where the secretion of calcium carbonate is ongoing.

That storage formed is called the ‘pearl sac’ which experiences growth as a result of cell division. The budding mantle tissue cells have a connection with the pearl sac’s inner surface because that is the avenue in which the secretion of columnar calcium carbonate occurs. When the time is due, the external mantle cells of the pearl sac moves on to the formation of tabular aragonite. The phase of the nacre secretion is when the brown pebble is covered with a nacreous coating. The pearl sac remains in a position all through the process of the shells growth. Years pass by which leads to the formation of pearls that will be mature enough to be harvested.

Pearls that come in uneven shapes are called baroque pearls. A little fun fact here, they do not always come in white, it could be black, blue, green, grey or red.

Do your initial answers to the question, “where do pearls come from?” match what you have learned so far? You would also be interested in knowing how cultured pearls come into existence. Cultured pearls are not sub-standard to natural pearls but are often less expensive than natural pearls. Cultured pearls and natural pearls can be distinguished with the use of an X-ray.

Cultured pearls are formed in a similar method with natural pearls but what is introduced here is intentionality. Here, a ‘pearl farmer’ (yes, there are pearl farmers) deliberately transfer a grain of sand in the mollusk (oysters) which are then transferred to the sea where they are able to mature for over a period of eight to thirty-six months. After this period of time, the pearl farmer checks for the pearl.

Another explanation for cultured pearl can be understood as a reaction of the shell to deliberate tissue implant, in this case, a graft which is mantle tissue that is from a donor shell is implanted in a recipient shell. This process causes pearl sac to form in which the tissue is then aware of calcium carbonate (In discussing natural pearl, we mentioned the importance of this). There are common names (trade names) associated with cultured pearls, some of which are;  

Black Tahitian: The black pearl oysters Pinctada margaritifera are found in Tahiti, Cook Islands, and Fiji. They are commonly referred to as black pearls and are valued because of their rarity (their rarity is often debatable). The oysters used in producing this breed of cultured pearls can only be nucleated one pearl at a time.

Keshi Pearls: This tricky because it mostly occurs as a by-product of the process of cultured pearls. These breeds are often produced in China which is likely because of an error in the culturing seeding process which is mostly in baroque shape.

Other types of cultured pearls are Akoya, Golden South Sea Pearls which could be in color white or gold and are usually grown in the Philippines, Indonesia, and Australia.

You have all the answers to the question, “where do pearls come from?” Hopefully, you now have closure on the origin of your favorite jewelry.


Written by Olanrewaju Arilomo








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