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Pearls, The Birthstone for June

Pearls, The Birthstone for June

                The legends of pearls have been spoken about since antiquity.
Pearls have been treasured as one of the most valuable of all gems; regarded as “tears of the Gods” in Persian mythology. The Chinese believed that pearls were jewels in the sea and grew by the power of the moonlight.

The oldest recorded pearl jewelry is 4,300 years old, found during the excavation of the king’s palace at the Persian capital of Susa and currently on display in the Egyptian Museum in Cairo.

In the thirteenth century Marco Polo visited the coasts of India and the Persian Gulf and recorded the labor of the local pearl divers. He described the divers as “being laden with weights and lowered to the seabed to gather pearl oysters while holding their breath.”

In 1913 the German zoologist Friedrich Alverdes established the exact scientific process to explain how a pearl is created from the oyster. Alverdes discovered that pearls are formed when a foreign body, such as a grain of sand, penetrates the shell of the oyster and the need to isolate the irritant the mollusk encases it with layer upon layer of a substance called nacre, which is calcium carbonate. As each layer of nacre is added, the pearl (covered irritant), becomes more iridescent.

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After six to eight years an oyster creates fine quality pearl that is lusturous due to a thick nacre. Pearls that are removed from an oyster after a short while will have a thin nacre and will look like chalk.

In 1904, Mise, Japanese carpenter, started pearl culturing experiments in 1904 and became the first person to develop a spherical, cultured pearl. However, Mise was not able to achieve a patent in China for his work.      


Based on Mise’ effort and knowledge, a zoologist named Nichikawa in 1907, also began producing spherical, cultured pearls. Upon Nchikawa's death his father-in-law, the noodle seller Mikimoto, took over the culturing project and created a company by achieving a patent.

Mikimoto named his new firm after himself, although he had no prior knowledge about culturing a pearl. Over the years the Mikimoto company has made great contributions to the development of the pearl industry. Because Mikimoto was long believed to be the originator of cultured pearls, the term Mikimoto Pearls is used incorrectly when referring to the finest cultured pearls. 

"What is the difference between Akoya and Mikimoto?

The method of culturing a pearl begins with opening the valves of a pearl oyster and inserting a small piece of mother-of-pearl shell. After a few years in a protected environment ( in their native water) the oyster will have covered the inserted shell with nacre.
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The longer the oyster is in the water the thicker the nacre becomes. A thick nacre deposit will create a pearl more lustrous and valuable. The only true way to detect a natural pearl (not nucleated by man) from a cultured pearl is to x-ray the nucleus, the original irritant.

Pearls are cultivated in many parts of the world. The largest pearls in the world are from huge oysters in the Australian warm waters. South Sea pearls are grown over 20mm in size and can be round or baroque in shape, with colors varying in shades of white, grey and golden. The most expensive of all pearls, and a strand of matching perfect, golden-round South Sea pearls are very rare. South Sea Pearl refers to a pearl cultivated from the waters of Burma, Indonesia, French Polynesia and Australia.


Cultured pearls produced from the Akoya oyster from Japan are called Akoya Pearl; this term refers specifically to a Japanese saltwater cultured pearl. The Japanese Akoya cultured pearls are round and oval to semi-baroque in shapes with natural colors of white, rose, and light-golden; ranging in sizes typically from 2mm-19mm.


The second most important saltwater producing mollusk is the giant conch, Strombus Gigas. Conch pearls produced from this shell have an opaque, naturally vivid pink color and are extremely rare. Orange pearls, called Melo, have a similar appearance to the conch pearl except for color are unique to the Malaysian, Myna Marian and Vietnamese waters.

Pearls cultivated from the waters of Tahiti are known as Black Tahitian Pearls. Not a true black, they are shades of grey to dark gunmetal blue with overtones of green, pink, lavender and brown. A lustrous black pearl should look metallic, with very few to no blemishes. Tahitian pearls range in sizes of 7mm to 30mm in shapes of round to baroque; round being the most valuable. Natural colors of the cultured Tahitian pearl should not be confused with the dyed black pearls from China.

Pearls found at random by divers are Natural Pearls. Natural pearls of the finest quality are from the Persian Gulf are traditionally called Oriental Pearls. Natural pearls have been found in the Gulf of Manaar, Red Sea, India, Australia, South Sea Islands of Micronesia and Polynesia, Japan, Venezuela, Gulf of Mexico, Panama, Pacific coastline.

Natural Pearls maintained a high value because of their scarcity prior to pearl culturing. Cartier Jeweler frequently tells the famous story relating to the value of pearls. In 1910, Mrs. Morton Plant sold her fabulous mansion at 52nd street and 5th Ave. in New York to Cartier for a strand of pearls worth one million dollars. Cartier still operates their store from the Plant mansion today.

Tahitian pearls are round, semi-round, drop, button, baroque and circle (rings around the pearl). South Sea pearls are round, semi round, circle and baroque.


Freshwater pearls are mostly baroque and come in endless varieties of shapes, often flat as rather than spherical. Chinese freshwater pearls are dyed or treated to give a range of colors which may be confused as natural Tahitian or Golden South Sea pearls so it's very important to purchase from a Gemologist or trusted jeweler.


Mabe pearls are a cultured blister pearl with a round top and tend to be very delicate. A blister pearl is a natural or cultured pearl that is attached to the surface of the shell, when they are removed from the shell they are flat on one side and covered in nacre on the top.

Seed pearls are very small natural pearls usually 2mm round. Keshi pearls are a byproduct of the oyster, a small pearl that can form in the muscle of the oyster in addition to the cultured pearl. They can be flat, oval, odd-shaped and usually has a poor luster quality.

Pearls are graded according to size, color, luster, surface blemishes and shapes. Some pearl companies have their own system of grading. For example, AAAA identifies the top quality pearl to A for the lowest quality. There is no universal set of grading standards and the A system is very subjective. Buying pearls from a Gemologist is recommended.

The size of a pearl varies on the type of oyster, location and the water temperature. The worldwide standard for measuring pearls is in millimeters. Pearls are sold based on the “momme”, which equals 3.75 grams in weight. Momme indicates the thickness of the nacre on each pearl, therefore a more valuable, lustrous pearl, (when measuring pearls of the same millimeter size) will weigh more. Pearl sizes typically range from 2mm to 20mm, in increments of half millimeters.

When a pearl does not have a smooth surface and has slight nicks, wrinkles, scratches, cracks, pits, dimples, bumps in the nacre, known as surface blemishes the value will be diminished.
A perfectly round pearl is the most valuable of all. The Japanese Akoya form round pearls more often than any other type of oyster. There are many oval shaped pearls that may appear round; the price of a slightly oval pearl will be considerably less.

When choosing a strand of pearls, the first thing to look for is matched size, color, roundness and luster. Pearls are traditionally strung on a special silk cord from Japan that are usually tied with a tiny knot in between each pearl to keep them separate and secure. When pearls are worn over the years the thread will stretch, if the pearl slides on the thread, it is an indication that it is time to have the pearls taken apart, cleaned and restrung. A 16” strand is called a choker; 18” strand a princess; 20” a matinee and 32” an opera. Any strand longer than opera is called a rope of pearls.

Pearls are a delicate gem that can easily be damaged or destroyed with perfumes, hair sprays and oils from skin. The nacre, or surface of the pearl, will dissolve from acids. Pearls should never be worn in water such as hot tubs, swimming pools or showers. Extreme heat can crack the nacre, if left in the sun or by a heater.

Pearls need to be cleaned with a soft, damp cloth, without the use of any detergents or cleaners. Never use any type of abrasive cleaners or abrasive materials or the pearl surface. 
Do not put pearls in ultrasonic cleaners or commercial jewelry cleaners. A damaged pearl can never be repaired because the nacre cannot be replaced. Pearls should be stored in a soft pouch or pearl folder. Safekeeping and treatment of pearls will ensure that pearls can last for generations.

UPDATE 11/5/20:  There is a lot of misinformation about the care and identifying cultured pearls on the internet and YouTube.  I've listed some correct information about 'identifying cultured pearls' and the identification.

1/. Do not rub cultured pearls against your teeth.  Cultured pearls are NOT identified by doing this; it can scratch the surface of pearls, diminishing the value.

2/ Many cultured pearls sold as "Biwa" and "Baroque" are incorrect.  Please use a Graduate Gemologist (with diplomas from the GIA) for identifying and correctly knowing the value of cultured pearls.


Janet Deleuse and Deleuse Jewelers in Fairfax, CA, sells only the highest quality pearls, hand-chosen by Janet & Jeff Deleuse.

       Have questions about purchasing pearls? call us: 415-459-3739

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