The answer has been sought after through the centuries. Fortunately for us...we live in an age of increased knowledge...so the process is no longer a mystery as it was for our ancestors of long ago.
We not only understand the process of how are pearls made naturally, but man has figured out
So, as there are sheep farms....there are now pearl farms...where pearls are the "crop."
In a nutshell
How are pearls made? For those of you who want a simple straight-forward answer in a few words:
How are pearls made in saltwater oysters? A saltwater pearl is made by inserting a mother-of-pearl bead nucleus(most often made from pigtoe clam shell from a USA river) along with a tiny piece of mantle tissue (living epithelial cells from another oyster) into the oyster. The mantle tissue forms a "pearl sac" around the bead and the oyster then coats the bead with nacre, which is the pearly substance.
How are pearls made in freshwater mussels?
A freshwater pearl is made a similar way, but the mother of pearl bead nucleus is eliminated. Freshwater mussels will make a pearl when only a tiny piece of mantle tissue is inserted inside. When multiple pieces of mantle tissue are inserted, multiple pearls are formed. (One reason freshwater pearls are usually a lower price....one mussel can create more than one pearl.)
How are pearls made?
Here is a more detailed explanation...for those of you wanting to understand more thoroughly the question: How are pearls made.
It all starts with baby oysters which are either artificially bred in a hatchery or allowed to spawn naturally as in Tahiti.
Baby oysters are put in cages and suspended in water, but not just any water will do...there must be an adequate food supply for the oysters.
A good combination for sea oysters is to be in a bay which is supplied by a freshwater river which brings food along with it, but too much freshwater can endanger the oysters life....so a delicate balance must be found.
Temperature is also important. Oysters like warm water...about 75 degrees is ideal...and sudden temperature changes can kill the oyster, and if not kill it, the quality of the pearl can be affected. To ensure the health of oysters, some pearl farmers move their oysters to warmer seas during the winter.
When the oyster is 2-3 years old....he can start his occupation of pearl growing.
How are pearls made?
Understanding the mother of pearl nucleus.
As stated in the nutshell explanation, a mother of pearl bead is inserted as a nucleus...but why a mother of pearl bead? The Chinese, in the 13th century were implanting lead Buddhas into mussels and the mussels in turn coated the Buddhas with nacre (pearl substance)...so essentially anything can be coated with nacre. But...drilling a hole in the pearl causes the nacre to heat and expand. It's important to have the nucleus made of a similar material...so the rate of expansion can be equal, otherwise the pearl can shatter.
For saltwater pearls the mother of pearl bead is essential. These mussels must be harvested (strict quotas must be followed here in the USA for removal of these mussels), steamed, meat removed and cleaned shells shipped to special factories which prepare these mother of pearl nuclei.
How are the nuclei prepared?
First, the shells are cut into large strips, then the rough outer shell is chipped from the inner shell and they are hammered into fairly small pieces and finally ground into round balls which vary in size from 2.5-8 millimeters, and polished until very smooth.
Now, the nuclei are sold to pearl farmers for implantation.
Insertion of the mother of pearl nucleus
Watch a Video of Pearl Nucleating.
In understanding how pearls are made, we know that early in the morning of the day an oyster will receive a nucleus, they are taken out of the water and placed in dry containers in a shady spot. After about 1/2 hour all the oysters will have opened their shells. At this point they are "pegged," meaning that a worker slips a wooden wedge into the crack to hold them open. If they don't open, they are returned to the water for another 24 hours.
Once pegged, they go to the "operating room"...a sunny room filled with well-trained experts who will perform the precise, and delicate implantation.
Each operator has strips of prepared living mantle/epithelial tissue to be inserted with the nuclei. One oyster must die to provide this tissue which is cut from its mantle and its rough edges cut away, for 14-15 inserted nuclei. Too bad...but that is how pearls are made. The strip of tissue is cut into tiny squares and stays alive for 2 hours...so must be used within that time frame.
The oyster is secured in a clamping device in front of the operator and either the wooden wedge is left in place or a retractor which allows the shells to be forced further apart is inserted. If the oyster is opened too far...it dies.
With dentist-like precision, the operator who has trained extensively and learned how pearls are made, quickly makes a 1/2 inch incision into the body of the oyster at the gonad or at the connective tissue. Then skillfully places the mantle tissue and nucleus (dipped in water and held by a suction tool) into this slit, being careful to get them directly next to each other. If not in direct contact, the pearl sac will not form.
Time to recuperate
The wedge or retractor are removed and the oyster placed instantly into sea water. This whole process takes less than 60 seconds...but the oyster will take the next 6 weeks recuperating from the shock.
After the "shock period" is over, the oysters are again raised to the surface and inspected and cleaned. Any oysters that didn't survive are discarded.
How are pearls made?
For 2-4 years the oysters are allowed to grow and will experience this process, continuing to layer the nucleus with nacre....making a lovely pearls....and providing rich rewards for its owner.
The process for freshwater pearls is similar, but no bead nucleus is needed and more than one square of mantle tissue can be inserted, as stated above, allowing for more than one pearl to grow in each mussel.
So...how are pearls made?...I hope you now understand the process a little bit more.