Coolest news story of the month: a fisherman in the Philippines recently revealed that he had been keeping the world’s largest pearl under his bed for the past 10 years. The monster pearl is one foot long, over 2 feet wide, and weighs 75 pounds!
Despite its gnarly appearance, the pearl has been declared to be worth over $100 million. The fisherman said he found the pearl in a giant clam while out fishing over a decade ago.
When we read this story here at Blue Door Beads, our first thought was “Holy moly! That thing is crazy huge!” The, our second thought was, “Huh…I thought only oysters produced pearls…?” And that got us thinking some more: what else don’t we know about pearls? Turns out, quite a bit. But now we’ve done some research and are ready to share some really interesting pearl facts with you!
Besides oysters, what other types of critters produce pearls?
Many salt- and freshwater mollusks, not just oysters, produce pearls. They may be formed in mussels, conchs, cowries, and scallops — to name a few — “and come in a rainbow of colors, depending on the species of mollusk.” (nationalgeographic.com) Although fairly rare, even giant clams have produced their fair share of pearls, including the Pearl of Lao Tzu and the as-yet-un-named pearl pictured above.
What exactly is a pearl?
It’s “an adaptation to get rid of a piece of schmutz,” explains Paula Mikkelsen, a biologist who studies mollusks at the Paleontological Research Institution in Ithaca, New York. “The mantle [the fleshy part of the shell] pulls calcium carbonate from the water and layers it around the intruding irritant” in an attempt to relieve the discomfort (nationalgeographic.com) The irritant is most frequently organic material, parasites, or even “damage that displaces mantle tissue to another part of the mollusk’s body.” These small particles or organisms can end up inside a mollusk when the shell valves “are open for feeding or respiration.” (www.wikiwand.com) In the photo below, you can see what a natural pearl looks like when cut in half:
The layers of nacre wrapped around the nucleus resemble a jawbreaker cut if half — although it’s not nearly as tasty-looking! Most pearls are a made of a combination of calcium carbonate, aragonite, calcite, and an “organic horn-like compound called conchiolin.” (www.wikiwand.com)
The reason why you don’t find a pearl in every wild mollusk is because, for the most part, mollusks are able to open their shells to expel any irritants. Scallops can even open their shells rapidly enough that they can travel quickly by “clapping.” (Here is an amusing short video!) This is why pearls used in the jewelry industry typically come from mollusk farms, where the critters can not only have uniformly-shaped “irritants” inserted into their shells — resulting in more uniformly-shaped pearls — but they can also be kept stationary (i.e. have their shells kept closed) by having nets placed over them.
Below is a diagram of the difference between a cross-section of a non-natural pearl that had an already-large round bead inserted inside it (usually made from a polished sphere made from a freshwater mussel shell), and a cross-section of a natural pearl that built its size up over time with many layers of nacre (pronounced NAY-kur):
So, while we’re on the subject…
What’s the difference between cultured pearls & natural pearls?
Turns out, in the modern-day jewelry and bead industry, almost all pearls are cultured pearls. This means they were created through human intervention of some kind, not created on their own out in the wild. Cultured pearls are supervised throughout their development; those supervising must ensure that the mollusk receives the food it requires and the surrounding water temperature remains consistent and pollutant-free. Consistency in these areas means pearls can be grown to be the same color, size, and shape. Cultured pearls can be either saltwater pearls or freshwater pearls.
To break it down, there are three types of saltwater cultured pearls, most of which can only be nucleated with one pearl at a time:
1. South Sea Pearls
South Sea pearls come in two colors: white and black. The white pearls are primarily cultured in the waters of northern Australia, the Philippines, and Indonesia and can vary from white, to light yellow, to gold (usually from the Philippine and Indonesian waters) from white-to-silver (usually from the Australian waters.) The black pearls are found “over a wide area from the Cook Islands to the Gambier Islands in French Polynesia.” (www.missjoaquim.com)
2. Tahitian Pearls
These are considered some of the most beautiful pearls in the world, ranging in color from charcoal gray to dark green and black. Tahitian pearls are only produced by the black-lipped oyster, which is only found around Tahiti and the French Polynesian Islands. The oyster itself is quite large, as much as 12 inches across and up to 10 pounds, which results in larger-than-average pearls. (www.missjoaquim.com)
3. Akoya Pearls
Considered to be the classic cultured pearl type, Akoya pearls are cultured in south-western Japan and China. Akoya pearls typically range from soft pink to “creamy silver” colors. “The Akoya breed of oyster is the smallest pearl-producing oyster used in pearl culturing. The resulting pearls also tend to be smaller, ranging in size from 2mm to 11mm and are consistently round or nearly round,” making them highly coveted in the jewelry industry.
The term freshwater pearl refers to a wide range of different shapes of pearls (such as potato-shaped, rice-shaped, coin-shaped, and many more), but can be summed up with one main definition: freshwater pearls are cultivated in mussels that live in fresh water lakes and rivers rather than oysters that live in oceans. The nacre of high-quality freshwater pearls does not typically have the glossy finish of Akoya pearls, “and they are evaluated on separate quality scales” than the chart pictured above (www.pearlparadise.com). Quite frequently, freshwater pearls are funkier in shape because, instead of inserting a perfectly round bead into the mussel, cultivators often add “a tiny piece of mantle tissue from a donor shell”; since the mussel is adding nacre to a non-solid item, the result is an irregular pearl. (www.wikiwand.com)
Which pearl colors are natural, and which are enhanced?
Pearls can commonly be found in a wide range of natural colors, including white, pink, silver, cream/ivory, and yellow. Pearls in darker colors (such as light brown, chocolate brown, green, blue, black, and purple) can also be found naturally, although they are much more rare. If you come across pearls that are in this darker color family and are inexpensive (i.e. less than a few hundred dollars), chances are the pearls have been enhanced with a bleaching-then-dyeing process. Check out the pictures below to see the wide variety of both traditional and non-traditional pearls that can be found in a variety of mollusks from around the world!
We hope you have enjoyed learning more about one of nature’s most interesting creations, and we also hope that the next time you come across pearls of any kind, you’ll think of the fascinating circumstances that helped make them possible!
All photos below (and info in captions, unless other wise noted) are courtesy of thepearlcollector.com, where you can find out more about other amazing pearls, such as scallop pearls, abalone pearls, and more!