Natural vs. Cultured

A natural pearl is created, as the name implies, by nature. All pearls grow around a core. The core of a natural pearl is simply a fragment of shell or fishbone, or a grain of sand that strayed into the unsuspecting pearl oyster’s shell. All this happens quite by accident or on the whim of nature. A cultured pearl is also grown by nature but with the assistance of man. In 1893, Kokichi Mikimoto discovered a way to duplicate this process of nature and not have to depend on fate to begin the process of growing these beautiful pearls. Eventually, he would develop and patent a process that would produce perfectly spherical cultured pearls. He found that he could insert a fragment of shell himself and then wait for nature to grow the thousands of layers of nacre that form a beautifully lustrous pearl. This process of growing cultured pearls continues today. Basically, the process begins when oysters are gathered from the sea at two to three years old. Then the culturing begins. A skilled technician inserts, by hand, a nucleus of pig-toe shell from the Mississippi River into the body of the oyster. The oysters are then returned to the sea where nature takes over the process, coating the irritant nucleus day by day with layer upon layer of nacre, the beautiful iridescent and pearly substance that lines the shell, to form a beautifully lustrous pearl. This human intervention of inserting the nucleus by hand into the shell, rather than waiting for nature, is what distinguishes a cultured pearl from a natural pearl. Only by the use of an X-ray to scan the nucleus can we determine the difference. Otherwise, there is no difference, particularly as far as quality is concerned, between natural and cultured pearls. Both are genuine.

 

The Process of Cultivation

As stated earlier, a nucleus of pig-toe shell is inserted into the pearl oyster. It is this irritant nucleus that will stimulate the oyster to secrete the layers of nacre that will ultimately form a pearl. But first, the oysters are placed back into the sea. They are put in wire-mesh baskets, to protect them from natural enemies, and hung from long, floating rafts. The rafts are often moved to protect the oysters from predators, extreme temperature changes, rough tides, etc. The oysters are then left submerged, during which time the pearly substance, nacre, forms around the nucleus. Several times a year, the oyster baskets are lifted out of the water and the oysters are carefully cleaned of all clinging material, such as moss and seaweed, barnacles, parasites and other marine life, and submerged again. After three to six years beneath the sea with careful cultivation, and depending on size and quality desired, the pearls are harvested. The oyster is opened and a beautifully lustrous pearl is found inside.

 

Kinds of Pearls

Akoya or Japanese Pearls

Most cultured pearls come from the seas of Japan and account for the majority of all the pearls on the world market today. A nucleus of pig-toe shell from the Mississippi River is implanted in the Akoya Oyster (Pinctada fukata) which produces pearls from 2-10mm. Their shapes range from round to irregular and although basically white, Japanese cultured pearls have tones of cream, gray, bblue, green, gold, silver, pink and pink rose. They are best noted for their rich colors and high luster and are among the most desirable in the world.

 

Freshwater Pearls

Freshwater pearls, often called Biwa pearls, are so called because they are grown in the fresh waters of Southern Japan, mainly Lake Biwa, and also in the Shanghai District of China. Freshwater pearls are produced by implanting a piece of mantle tissue from a mussel, rather than a solid nucleus. This tissue dissolves and the pearl becomes nacre through and through, but it is still cultured because of the original insertion by man. They come in pastel shades of lavender, peach, and tangerine as well as ocean colors (blue-greens), and are easily recognized by their odd shapes which are elongated and free form in appearance. The flat shapes resemble rice or raisins and some look more like nuggets.

 

South Sea Pearls

Generally speaking, cultured pearls larger than 10 mm are produced in the warmer waters fo the South Seas by the larger oysters (Pinctada maxima) which are capable of producing these exotic gems known for their rare size and exquisite colors. Large silvery pearls are produced by the large Silver-lipped Pearl Oyster which thrives in the warm waters of Australia, Burma, and the Philippines.

 

The most treasured, however, are the beautiful and brilliant golden pearls, produced by the Golden-lipped Pearl Oyster. The enchantment of these beautiful gems comes from the rich, high luster for which they are known. Ranging in size from 10 to 16 mm, their warm, natural golden color is said to be rarer than gold itself.

 

Naturally Black Pearls

Produced by the Black-lipped Pearl Oyster and approximately 8 ½ to 15 mm, naturally black pearls from Tahiti and Okinawa have blue, green and violet tones or a fancy peacock effect. The rare sizes and mysterious color of these enchanting gems are in limited supply and command a high price today. It may take a dozen harvest years to collect enough black pearls from each harvest that will match in size, shape and color to create one necklace.

 

Pearl Quality Standards

Luster and Nacre Thickness

For beautiful pearls, the most important factors are luster and nacre thickness. Luster is both the surface glow, as well as the deep, mirror-like reflection and refraction of light. Think of it as the inner light. The nacre thickness is largely determined by the length of time the pearl is in the oyster. The thicker the nacre, the higher the value. The luster and nacre of the pearl are the two primary considerations in the grading process. Examine pearls on a solid background, not on a glass showcase, and you will be able to see the beautiful luster of a cultured pearl.

 

Color

There is an infinite variety of colors in pearls that range the entire color spectrum. We find subtle shades of cream, gray, green, blue and pink. The most popular, however, are white and pink rose because these shades flatter the widest range of skin tones. Color is a matter of personal taste, but whatever the color, it should be rich and even throughout. Careful sorting and matching of colors is an important factor of the grading process.

 

Shape

Just as there are many colors of cultured pearls, there are also a number of different shapes. Generally speaking, the rounder the pearl the more desirable. Some pearls are not quite round upon careful examination. Other shapes are popular as well, when a different look or style is desired, such as the tear-drop or pear-shape, the semi-round or oval, the button and the baroque, which is irregular and free form in shape. Surface Perfection Remember, pearls are produced by nature. Tiny marks seen on pearls are part of their natural texture, like fine raw silk, and do not detract from their beauty or value unless they are excessive. Large, noticeable blemishes in the surface reduce value considerably, but small marks are a sign that the pearl is genuine. The cleaner the pearl, the higher its quality. This is a major factor in evaluating pearls.

 

Pearl Measurement

The industry states the size of pearls metrically, in millimeters, such as a 6 mm pearl, meaning that the diameter of the pearl is 6 mm. The length of a necklace, however, is measured in inches, such as a 16 inch choker.

 

Necklace Lengths

Choker	approximately 15 inches
Princess	approximately 18 inches
Matinee	approximately 22 inches
Opera	approximately 30 inches
Rope or Lariat	approximately 40 inches or longer

 

Graduated Necklaces

(larger pearls in front, gradually smaller toward back)

6 x 3 mm	approximately 16 inches
7 x 3 ½ mm	approximately 18 inches
8 x 4 mm or larger	approximately 19 inches