Shimmering, ethereal, translucent and magical, for thousands upon thousands of years, pearls have been one of mankind’s most sought-after treasures, one of natures greatest mysteries, since the dawn of civilisation.

In this posting we’ll be looking at what pearls are, where they come from, how they’re formed, and how they have been cherished, treasured, and hunted for by countless millions of people across millennia of time.

What is a Pearl?

A ‘pearl’ is the name given to the hard, glossy, smooth and shimmering secretion formed inside of a hard-shelled mollusk (a type of shellfish), usually round in shape, and ranging between a few milimeters, to a couple of centimetres in diameter, depending on the size of the mollusk, and the age of the pearl.

What are Pearls Made Of?

Pearls are made of a sticky, glossy secretion produced by the mollusk – a kind of slime or goo or gel, which is used by the mollusk as a defense mechanism. This secretion is known as ‘nacre’, or more commonly, as ‘Mother of Pearl’, because it’s the substance that ‘mothers’ or ‘births’ the pearls that are found inside oysters.

How are Pearls Formed?

Pearls – which may be freshwater, or saltwater, and which can vary greatly in size, colour, and shape, depending on the circumstances of their creation – are formed when an intruder (organic matter of some kind, such as a parasite, worm or other living creature) breaches the mollusk’s outer defenses (the shell), and tries to attack the mollusk itself.

To defend against infection, parasites or attack, the mollusk expels a gob of liquid nacre, which will drown and envelope the invading organism, stopping it from carrying out its dastardly deed of killing, or infecting the mollusk, or of trying to make the shell its new home. The nacre hardens, and the mollusk will continue to expel more and more nacre over the offending intruder over time. With each successive secretion, the nacre will harden, and form layers of glossy enamel over the top of existing layers.

Finally, the nacre shell over the intruding matter will grow large enough that the oyster will consider it safe enough to detach the nacre-encrusted organism (aka – a pearl!) from the interior wall of the shell in which the mollusk lives – and the pearl will simply sit in the oyster or mussel or abalone – until it is expelled if or when the oyster next opens its shell. If it isn’t, or can’t be removed by the mollusk, then the pearl remains inside the oyster until it might, possibly, be found by humans!

This is what creates pearls, and causes them to grow. The size of the pearl, and its colour, depends on the colour of the mollusk, the size of the shell which the mollusk lives in, and how long it decides it has to attack the intruder, before it feels safe again. The pearl’s shape is determined, again by the size of the mollusk, but also by the shape and size of the intruder which has triggered the mollusk’s defense mechanism.

Along with making the spherical baubles known as pearls, nacre is also the substance that creates the very shells themselves which the mollusks call home. The only difference between the shell, and the pearl, is that the shell is the hard, protective receptacle for the mollusk inside, whereas the pearl is formed (through similar processes) to protect the mollusk from anything that bypasses its first line of defense.

Diving for Pearls

With enough determination, anybody can find a gold mine, or a silver mine, or even a cluster of gemstones hidden inside the Earth. The veins of ore having been discovered, just need to be dug out, crushed, extracted and refined.

Finding pearls, by comparison, is much harder.

While there are countless millions of mollusks of all kinds in the world’s oceans, from oysters to abalones to mussels, only those which have been attacked, and have had their shells breached or otherwise compromised by an invader, might produce a pearl. Only those pearl-bearing mollusks which exist within the range of free-diving water-depths might be found by humans, and only a small percentage of those found will even have pearls inside them. In fact, the chances of finding a pearl in an oyster is something along the lines of 1 pearl per 10,000 mollusks – a 0.01% probability.

Along with the sheer randomness and rarity of pearls – especially – of finding enough pearls of the same size for use in jewelry-making – was the risk entailed in finding pearls.

Anybody can dig a hole and search for diamonds, or shovel the soil from a riverbed to pan for gold – but diving – sometimes several tens of meters – to find pearl-oysters and abalones – was a disorienting and dangerous profession – one which dates back to prehistory in many parts of the world, ranging from Madagascar to China, Greece and Italy, and Indonesia to the Philippines. The risk of drowning, decompression sickness, paralysis, disorientation, or being attacked by sea-creatures – all added to the mystique of pearls.

It is for all these reasons that pearls, for centuries and centuries and centuries, dating back for thousands of years – have been considered one of the most valuable gems ever. The sheer randomness of being able to find a pearl out there in the deep, swirling depths of the oceans is what made them so treasured.

Myths about Pearls

Given the rare and random nature of pearls, it is not surprising that there’s loads of myths about pearls, such as the fact that pearls are formed inside oysters from constant irritation of the mollusk inside. This is not strictly true – pearls are formed due to ONE irritant at a time entering the shell, against which the mollusk defends itself.

Another common myth is that all pearls are perfectly round spheres! Again, this is not true. In fact, it’s so not true that perfectly round pearls are probably the hardest types of pearls to find! In truth – pearls can be almost any shape. Being organically and naturally formed, the shape of pearls is dictated by the size of the mollusk, and by the size or shape of the irritant or invader which caused the mollusk to start forming a pearl in the first place.

Irregularly shaped pearls – which can be anything from flat discs to ovals, pill-shaped or pear-shaped – are called “Baroque” pearls – referring to their erratic shapes and lack of uniformity. In fact, finding enough perfectly round pearls of the same size, shape, and colour to form an entire pearl necklace is a feat so difficult to accomplish that for centuries, pearl necklaces were considered to be one of the greatest status symbols in the world! Literally hundreds of pearls would have to be found, sorted through, and finally, drilled and threaded – in order to create such a piece of jewelry – a feat which could take months, or even years to accomplish.

Pearls as Status Symbols

Because of the significant difficulties in finding pearls, and of finding enough of them to make jewelry with, pearls have been seen as a status symbol since the times of the Ancient Romans. Emperors, kings, queens, dukes and princes, have all used pearls as jewelry at one time or another. Indeed, pearls were so hard to find that they were often more highly prized than most other jewels – such as diamonds, for example!

Baroque pearls – those of irregular shapes – were often used to adorn crowns and coronets, because their odd shapes lent themselves to artistic creativity. This can be seen, for example, in the pearl tiara of the Empress Eugenie of France.

A String of Pearls

In the history of gems and jewelry, there are numerous famous stories. The Hope Diamond, the Star of India, and the Plant-Cartier Necklace!

…You’ve never heard of the Plant and Cartier necklace?

Morton F. Plant, a wealthy New York City financier and philanthropist, owned two houses in New York City in the early 20th century. Deciding that his original house was too close to Manhattan’s bustling commercial district of Fifth Avenue, Plant commissioned the building of another mansion (completed in 1916), further away, to give him more comfort and privacy.

The problem was finding a buyer for his original house – until his wife, Mae Plant – informed her darling husband that she wanted a new pearl necklace!

At the same time, Pierre Cartier, grandson of the founder of the famous, French jewelry house, was looking into expanding his family’s business further abroad. Cartier already had a commercial presence in Paris, and now London, but he was determined to go even further, and try and break into the American market! The only challenge was that he needed a commanding, central location on Fifth Avenue! Surely, nothing else would suffice!

When he heard that the Plant Mansion was up for sale, Cartier immediately became interested, but despite nonstop haggling and debating, neither Cartier, nor Plant, could come to an agreement on price – until Plant told Cartier that his wife was looking for a new pearl necklace!

Seizing on any opportunity to buy the Plant mansion, Cartier told Plant about a stunning pearl necklace that he had in his possession – 128 flawless matched pearls in a double-strand! The most perfect gift for Madame Plant, surely! As Cartier suspected, Plant was immediately interested. After all, the pearls only cost $1,000,000…

Finally, Plant agreed! $100 cash, and a $1,000,000 pearl necklace, in exchange for prime real estate on Fifth Avenue! Plant was happy because he got the pearl necklace that his wife was so eager for, and Cartier was happy, because he got the central New York location that he was so eager to buy! Mrs. Plant owned the necklace until her death in 1956!

As for the Plant mansion on Fifth Avenue? It has remained Cartier’s most famous New York location for over 100 years! The company took formal ownership of the building in 1917…and hasn’t left since!

Cultured Pearls

In 1917, a pearl necklace was enough to buy a house. A very, very nice house.

In 1918, a pearl necklace would be lucky to buy you a car!

This was because of something dramatic which happened in 1917, which turned the entire jewelry industry upside-down!

Since time immemorial, pearls had been naturally formed – discovered by chance on the seabed by divers and fishermen who scooped oysters and mussels up from the depths, to find these lustrous baubles shimmering inside their shells. Finding a pearl – any kind of pearl – was entirely a matter of luck. This immense rarity was what made them so incredibly valuable. But everything changed when, thousands of miles away from Plant, Cartier, and their New York real-estate deal, a man in Japan discovered how to grow pearls!

That man was Kokichi Mikimoto.

Building on discoveries made by Australian, and other Japanese researchers, that pearls are formed when an irritant enters an oyster, Mikimoto was one of the first people in history to successfully use this knowledge to create a pearl in an oyster through human intervention!

Thus began the age of cultured pearls.

Cultured pearls are created when a human agent inserts an irritant, or ‘nucleus’ (either shell fragments or pieces of mantle from another oyster) into a living oyster. The oyster, thus irritated, will start to secrete nacre around the intruder, growing a pearl, replicating what would have happened in nature anyway, but in a more controlled environment. This increases the yield of pearls, or at least, the chances of finding one – but it does not speed up the creation of pearls. You might still get a pearl, and you may get more than one, but they’ll still take months, or even years to form!

That said, creating cultured pearls is not nearly as easy as you might think! Remember – pearl formation is largely down to luck – even when human intervention takes place! Of 100 oysters manipulated in this way, maybe 50 might produce pearls, and of those fifty, maybe five might produce pearls of usable size and shape. There’s still a lot of guesswork and patience, even if you have tampered with the deck.

0.01% for natural pearls. 5.00% for cultured pearls. While that’s a significant jump in the chances of finding pearls, they’re still fairly rare. In the 21st century, natural pearls – those formed by chance – comprise just 1% of all pearls, and the other 99% are made up of cultured pearls.

While cultured pearls are cheaper because they can be produced more readily, differences in quality still remain. While on the outside, they might look the same, the difference is only seen when the pearls are cut open (or x-rayed). To increase the chances of pearl-formation, the irritant placed inside the living oyster is usually quite large – between 5-8mm across! This might not seem large, but when you consider that most pearls only grow to around 1.5 – 2.0cm in diameter, that irritant is taking up a lot of space!

So what’s the trade-off?

Pearl farming or oyster farming allows mankind to produce pearls more readily, and of a more uniform shape and size. It’s not an exact science – but it does greatly increase the chances of making pearls. The trade-off in manmade vs natural pearls is the quality of the pearls produced.

Natural pearls, formed by chance in the ocean – usually have very small irritants – a wisp of organic matter or a tiny parasite entering a pearl-oyster might create a pearl – but when it does – the pearl formed will be comprised almost entirely of nacre, with the irritant that caused its creation being only a tiny, almost imperceptible speck inside the pearl.

By comparison, manmade, cultured pearls, rely on much larger irritants to greatly increase the chances of pearl-formation. The result is a pearl that will have a very large irritant or nucleus, buried under the nacre.

What’s the problem with this? Well – if the pearl cracks, or splits, or is damaged or altered while drilling or cutting (to make jewelry, for example), then the nucleus is much more evident (a speck 5mm across in a pearl only 10mm wide, is going to be pretty obvious!). Because of the size of the irritant or nucleus used to form cultured pearls, the layers of nacre over the top are much thinner, more fragile, and more prone to damage.

It is because of this that cultured pearls, while more common, are cheaper, and natural pearls, being extremely rare, are still very expensive.

The difference is most clearly noticeable under an x-ray, or when a pearl is sliced in half. A cultured pearl has a larger nucleus and a thin outer layer of nacre, while a natural pearl will have a tiny nucleus, and several overlapping layers of nacre – similar to the rings on a tree.

Although natural pearls are, of course, of much higher quality – the creation of cultured pearls flooded the market, and caused pearl values to plummet almost overnight!

Remember Mae Plant’s pearl necklace? Sold in 1917 for $1,000,000, 40 years later, when she died in 1956 and it was sold at auction by her children, it fetched just… $150,000. By then, cultured pearls were so common that even a large double-strand of natural pearls were not seen as being particularly valuable anymore.

Shells and Mother of Pearl

So. We’ve covered pearls, we’ve covered oysters, we’ve covered cultured pearls…but what about mother-of-pearl? What’s that?

Mother of Pearl, or nacre, the substance that forms pearls – is secreted by the mollusk (oyster, abalone, clam, etc) – inside its happy little home – the shell.

As nacre is the mollusk’s natural defense mechanism, there’s usually a lot of it lying around, and the insides (and even outsides!) of shells are often coated in thick layers of this shimmering, glimmering, literally pearlescent material.

Because of this, mollusk shells (everything from large abalone shells, to smaller oyster shells, or even the shells of the mighty, chambered nautilus!), are often just as prized as the pearls they produce. Often called mother-of-pearl (to differentiate between the pearls themselves), mollusk shell nacre is commonly used in all kinds of applications, either for jewelry, or other types of decoration and embellishment.

Knife handles, razor scales, cutlery handles, jewelry, box-lids, cufflinks and countless other items can be made of (or decorated with) mother of pearl.

Mother of pearl for decorative purposes is sourced by using the leftover shells from mollusks. Once the shell has been emptied of its contents (the tasty, tasty mollusks, and any pearls that they might contain), the shell itself is cleaned, sanded, and polished. Almost every mollusk shell will have some sort of growth on the outside – barnacles, seaweed, etc, which will obscure the outermost layer of nacre on the surface of the outside of the shell, and with great care, this must be removed. Using progressively finer abrasives, the encrusted sand, barnacles and other detritus can be scraped and polished off of the shell’s surface, and the glimmering nacre underneath can be exposed! Now all the remains is to polish it to a glossy, reflective finish!

Especially large mollusk shells with beautiful nacre have been used to make everything from caskets and caddies, to trinket dishes, sewing cases, and even jewelry boxes.

The relative ease with which mother-of-pearl, as opposed to pearls themselves, may be found, has therefore made it one of the most popular decorative materials to work with for centuries. Easily carved and shaped, and able to be polished to a lustrous shine, it remains popular even today in everything from jewelry to pocketknives, buttons and hair-accessories.

Pearls in Fiction and Literature

Their rarity, size, colouration, shape and expense made pearls extremely popular plot-devices in fiction, myths, legends and ancient fables.

The very first work of fiction to feature the serial killer, Sweeney Todd, was titled ‘The String of Pearls’. Pearls are mentioned in the bible, and in the writings of Ancient Roman historian and statesman, Pliny the Elder (whose nephew, Pliny the Younger, wrote one of the most vivid eyewitness accounts of the eruption of Mt. Vesuvius in 79AD).

Even Sherlock Holmes tangled with pearls, when, in 1904, Sir Arthur Conan Doyle published “The Six Napoleons”, which featured “the famous Black Pearl of the Borgias!” as the priceless jewel stolen from the hotel-room of an Italian nobleman.

Want to Know More?

There are many excellent videos on YouTube about pearls and oysters, some which I found particularly interesting, were…