Pearls

On the nature of pearls

Pearls are formed by a variety of mollusks, including mussels, clams, oysters, snails, conch, and abalone.  An irritant, one way or another, finds its way int the shell of the mussel.   Once it enters the interior tissue called the mantle, the mollusk realizes it has been invaded by a foreign body and begins to defend itself by secreting a substance called nacre. Also known as mother of pearl, nacre is made up of calcium carbonate and conchiolin.  Not only is nacre used by the mollusk to form its shell, it is also used to encapsulate any intruders.  Over time and after several nacre secretions, the encapsulated irritant (perhaps a parasite or a bit of shell) becomes a pearl. 

Akoya pearl oyster, Pinctada fucata.  Image from the Gemological Institute of America.

Akoya pearl oyster, Pinctada fucata.  Image from the Gemological Institute of America.

Sometimes a foreign body is not even necessary for the formation of a pearl. If the outer lining of the mantle, called the epithelium, is drawn deeper into the mantle for some reason (such as an injury), this alone can stimulate the processes that produce a pearl.

Natural pearls

Natural, or genuine, pearls are pearls that are created by the movements and processes of nature, without human interference.  They can be found in both salt water and fresh water environments. Some sources say that about one in 30 - 40 oysters contains a pearl.  And when considering a pearl of gem quality, the ratio becomes even more drastic.

Several natural pearl strands and a large single pearl from the Arabian Gulf.  From the Gemological Institute of America.

Several natural pearl strands and a large single pearl from the Arabian Gulf.  From the Gemological Institute of America.

Sea pearls are typically found in warmer regions such as Northern Australia, Burma, Phillippines, and the South Pacific. The Persian Gulf has been considered the best source of sea pearls for a very long time.

While river pearls were once fished in the rivers of Asia and North America, and more notably in Europe, the industry (and often the pearl mussels themselves) is almost extinct today. 

On the culture of pearls

In 1893, at the age of 35, Kōkochi Mikimoto successfully created his first cultured pearl. 26 years later, he introduced his pearls in London, where they created a sensation. On one hand, Mikimoto's pearls were gorgeous -- and perfect.  Their color, luster, and shape were all flawless. The only indication that they were not genuine pearls, in fact, was their perfection. On the other hand, natural pearls had been worth a small fortune due to their scarcity. Facing a market filled with beautiful, farm-raised pearls, jewelers and other pearl-owners stood to loose a substantial percentage of their investment.  Indeed, Mikimoto had been known to say that he wanted the market so full of pearls that women could buy necklaces for two dollars.

"Perfect" pearls are more common under cultivation.  This is a strand of  12 - 15mm white fresh water pearls.

"Perfect" pearls are more common under cultivation.  This is a strand of  12 - 15mm white fresh water pearls.

The process of making a cultured pearl begins with a pearl-grafter.  He or she relaxes a two-year-old pearl mollusk in a warm bath.  Once the shell opens, the pearl-grafter makes an incision in the cell lining of the mantle and inserts a mother-of-pearl bead that has been wrapped in mantle tissue from another mollusk. This tissue then continues to grow and performs like a pearl sac in which nacre is secreted. The prepared mollusks are kept in underwater in cages for three to four years while the nacre layers build up and then the pearls are ready for harvesting.

Large blue-gray keshi pearl in swirled rose gold mounting accented with diamond melee.

Large blue-gray keshi pearl in swirled rose gold mounting accented with diamond melee.

Types of cultured pearls include:

  • Akoya: lustrous, round, white
  • Baroque: irregular and interesting shapes, flashes of iridescence, beautiful tints of color, pools of nacre, can occur naturally as well
  • Biwa: freshwater, oval, barrel shape, coin shape
  • Blister: domed, solid, high luster
  • Keshi: all nacre, an "accident" in pearl cultivation, small, baroque shape, almost all colors
  • Mabe: domed, very fragile, hollow and filled with epoxy
  • South Sea: large, thick nacre, various shades from white to pink and white to yellow
  • Tahitian: Grey to black

Historical notes and other interesting facts

  • One of Julius Caesar's motives for attempting to invade the Britain Isles in 55 B.C. was to capture the pearls that grew in the river mussels.  For many centuries, Scotland was known for its rose-colored pearls, Cumbria for its black pearls, and Ireland for white.
  • An ancient legend holds that Cleopatra dissolved a pearl from her earring in vinegar and drank it in order to win a competition she had with Mark Anthony to see who could throw the most extravagant party.
  • In his third voyage to the New World, Christopher Columbus journeyed to coastal Venezuelan villages where people wore bracelets of pearls and traded the gems for buttons, scissors, and needles.
  • In the 1500s, cataracts were also known as pearls.
  • When Philip II of Spain married Mary I of England (Mary Tudor) in 1554, he presented his queen with a pear-shaped pearl weighing 223.8 grains (11.2 grams).  With a history spanning more than 500 years, this is one of the most famous pearls of all time and would become known in the 1800s as "La Peregrina."  It has led an exciting life passing from the hands of an African slave in Panama to crowned heads all over Europe, from Napoleon III to Elizabeth Taylor.
  • Queen Elizabeth I had over 3000 gowns decorated in pearls and 80 wigs embroidered in pearls.  She had chests of pearl jewelry: strands, earrings, rings, pendants, and more.
  • The Pearl of Lao Tzu (Pearl of Allah)  is the largest known pearl in the world.It was found in the Philippines and, although it is not a gemstone pearl, its size is magnificent.  It is almost nine and a half inches in diameter and weighs just over 14 pounds.

Caring for pearls

  1. Store separately in a soft pouch (not an airtight container) to protect from scratching the pearl's surface on metal edges, prongs, stones, etc.
  2. Put your pearls on last -- after you've donned your makeup, perfume, and hairspray.
  3. Do not let vinegar, ammonia, or chlorine ever touch your pearls.  In addition to the cosmetics listed above, also avoid ink and, yes, toilet water.
  4. Before putting your pearls wipe, wipe them gently with hot, damp, soft cloth to remove body oils and perspiration.
  5. Don't wear your pearls while you work out or engage in other strenuous activity.  Don't wear pearls and sweat.
  6. Occasionally, clean your pearls.  Use a mild non-detergent soap to make a warm sudsy water and wash gently with a soft cloth.  You can use a soft brush to clean around the knots.  Alternatively, you can bring them in to Grimball's and we'll clean them for you.
  7. If your pearls get really dirty, you can wipe them or soak them briefly in acetone.  Or, again, bring them into the store and we'll clean them.
  8. Do not store in an excessively dry place.  Pearls need a certain amount of moisture in their environment.
  9. Periodically have your pearls restrung. Pearls should be strung on silk with knots in between in each pearl to prevent rubbing, which will wear away the nacre.
  10. No ultrasonic cleansing.
Teardrop-shaped baroque pearl on an 18K yellow gold lariat-style necklace with 0.1ct diamond accent.


Teardrop-shaped baroque pearl on an 18K yellow gold lariat-style necklace with 0.1ct diamond accent.

Resources and further reading

Jewels: A Secret History. By Victoria Finlay.  An non-fiction adventure through time and place exploring the history of gems.

The Pearl Book: The Definitive Buying Guide. By Antoinette L. Matlins, PG.  A comprehensive, yet engaging, read covering the history of pearls, how they are formed, cultivation, types, care, and quite a lot more.

Pearl. From Wikipedia. An entry covering several topics including the creation of a pearl, farming, history, and religious references.

Gemstones of the World. By Walter Schuman.  Our go to book at Grimballs.