News

Cultured Pearl Evolution

Originally posted on June 8th, 2017

Updated on April 13th, 2020

Last week, we talked about the different species of pearl-bearing mollusks on the Moijey Blog. We also chatted about how most pearls are cultured by humans for the gem and jewelry industry. That was a Reader's Digest version. We're going into more detail about cultured pearls.

For centuries, people cherished natural pearls, long before pearls were cultured by humans. Natural pearls don't have a mother of pearl bead center, called a nucleus. The center of a natural pearl can be a variety of things: it could be either a parasite or a worm. The myth that a grain of sand as the source of starting a pearl is indeed a myth. Either way, there's an irritant in the mollusk, and it secretes nacre to protect itself from the irritant being, well, irritating. After growing in their respective oysters, the pearls were harvested and presented to royalty and the wealthy, who cherished these beautiful jewels for centuries.

 

 

Prominent sources for natural pearls throughout history have been in Sri Lanka, the Persian Gulf, European rivers, and the rivers and lakes of China. During the third and fourth voyages of Christopher Columbus, they discovered that present-day Venezuela and Panama had pearl sources.

After years of harvesting from the mentioned sources, the production of natural pearls started to decline after 1900 for a variety of reasons—oil drilling, which led to industrialization, polluted oyster beds, and reduced natural pearl supply. Plastic buttons, oddly enough, were also responsible for the natural pearl decline. In the 1920s, plastic buttons were mass-produced and replaced mother-of-pearl shell buttons. With the reduced demand for shells, the declination for natural pearls also happened from developing methods of pearl culturing also led to the decline of natural pearls.

Despite the previous reasons for their declination, natural pearls still exist and can be found. But it doesn't make sense financially to harvest mollusks for natural pearls. Divers would have to search through hundreds, maybe even thousands, of mollusks to find one natural pearl that is of high quality. That is why we focus on cultured pearls for accessible quality.

The research to develop cultured pearls began in 1888. After many years of experimenting, Kokichi Mikimoto, one of the researchers, developed the first cultured pearl successfully in 1893. When I say successful, I mean that Mikimoto was able to produce spherical pearls, one of the most desired pearl shapes in the industry. By 1920, Mikimoto began to market his cultured pearls - which were Akoya pearls - internationally.

The process of culturing pearls, which is a variation of how pearls form naturally, begins as follows: First, pearl technicians take mantle tissue from another mollusk of the same species. Then, the tissue, along with a bead of carved mother of pearl, is inserted into the host mollusk's gonad. The insertion is done by a highly skilled technician with little to no discomfort to the mollusk.

With the bead method, the mantle tissue will grow and form a pearl sac inside the gonad, and the nacre will be secreted onto the bead, creating a cultured pearl. A bead and a piece of mantle tissue are needed to produce saltwater pearls, and freshwater cultured pearls need only a bit of mantle tissue to start the culturing process. Culturing pearls usually takes four to six years. When the operation finishes, the same mollusks will be used two or three more times, depending on the mollusk's age and condition.

Then the pearls will then be cleaned and  - depending on the nature of the resulting pearls - will be bleached to achieve color uniformity or dyed to a variety of desired colors. These practices are standard in the gem and jewelry industry, as long as there treatment disclosures to consumers.

 

Thank you for your time with us at Moijey. It's remarkable what needs to be done to produce beautiful pearls. Don't you agree? We hope you enjoyed reading about pearls as much as our gemologist enjoyed writing about them.

Next week, we'll talk about another June birthstone and one of my favorite gemstones of all time: moonstone.