It’s still pearl month and I am basking in the luster of my favorite organic gemstone (Shhh, don’t tell my middle name, Amber, that PEARLS are my favorite organic gemstone… [Yes, my middle name is a gemstone]).
Last week, we looked at the difference between natural and cultured pearls. This week, let’s talk about the steps that go into culturing a pearl.
How are pearls cultured?
Cultured Pearls are grown in a semi-controlled environment known as a pearl farm. There, mollusks are raised to maturity and then cared for as they grow a pearl around an irritant that is inserted into the animal by a person.
To initiate pearl development in salt water mollusks, a pearl technician implants a small bead, called a bead-nucleus, along with a piece of tissue from another mollusk into the host mollusk through a delicate surgical procedure. For freshwater pearls, small pieces of mantle tissue are implanted without a bead-nucleus. In both cases, the mantle tissue grows into a pearl-sac that will be the location for forming the cultured pearl.
The mollusk is then placed in a tank where it is monitored after surgery to ensure it does not die, go
into shock, or eject the bead-nucleus. Once the mollusk has recovered from surgery, it is placed into open water at the pearl farm, suspended in nets below the surface of the water. By placing the mollusks in nets, technicians are able to monitor the health of the mollusks over the course of pearl formation. Technicians are able to see if the mollusk has rejected the bead and they are able to scrub the creature clean of barnacles and other potential parasites in order to keep the animal healthy while it makes a beautiful pearl.
There are certain environmental hazards that can disturb or destroy a pearl crop including storms, pollution and either excess or too little available nutrients in the water. Another major problem is overcrowding. Overcrowded pearl farms can reduce the amount of nutrients and oxygen needed for the pearls to thrive while increasing the likelihood of disease among mollusks.
Different mollusk varieties produce different types of pearls and each requires a different amount of time to produce a pearl. Culturing time takes anywhere from 2 months to over 2 years! Every variety is prized for different features, which I will get into in a later post!
So what happens after a pearl forms?
Harvest: Some mollusk varieties can produce more than once in a lifetime, while others must be sacrificed to harvest the pearls. During the harvest, the mollusks are taken from the water and the pearl is delicately removed in a surgical procedure for those that are able to produce pearls again. Otherwise, the mollusk is sliced open, the pearl is extracted, the oyster is used for fertilizer... A little brutal, but beautiful?
Cleaning: Once the pearls have been harvested, they need to be cleaned because: oyster slime. Many pearls are tumbled, or buffed, to improve luster. Tumbling involves placing the pearls in a vat with a minimally abrasive organic material, such as ground husks or bamboo shoots.
Bleaching: Pearls are routinely bleached. This is an industry accepted practice. Pearls are soaked for
up to six months in a weak solution of hydrogen peroxide similar to that used in dental practices to whiten teeth. This process brightens and evens out the surface color of the pearl. It also brightens the conchiolin (the organic "glue" between the nacre coating), which is normally a brownish color.
Dyeing/(Irradiation): Some pearls are tinted using a weak dye solution to improve the rosé overtone. This process is referred to as “pinking.” Other pearls are sometimes heavily dyed unnatural colors or irradiated to give the pearl a metallic sheen. This is a very common practice with freshwater pearls on the market.
(Coating): Also to improve luster of pearls in the industry, you may see a colorless coating applied to restore some of the luster that was lost in the bleaching process or make a dull pearl SEEM lustrous. This step is not as common as the others. I, for one, would not purchase a pearl with a protective coating as this coating will deteriorate over time and alter the appearance of the pearl. Misleading!
Culturing pearls is a very labor intensive process. With months, often YEARS, invested in a single harvest that can be easily affected or destroyed by the environment or disease, it is amazing that we have so many pearls in the world.
But not all pearls are created equally! Next week I will talk a bit about the Value Factors by which we determine the quality of every pearl!