There are two types of Pearls commonly used in jewelry today. The two categories that Pearls fall into are Natural Pearls or Cultured Pearls. Natural Pearls are found in oysters and were formed without the help or influence of man. The Giant Silver Lipped and Gold Lipped PINCTADA MAXIMA oysters of the South Seas, produce most of the worlds large natural Pearls. A Pearl is formed when a piece of sand or other foreign substance enters into the living membrane of an oyster. The oysters reaction to the irritant is to secrete a substance called "nacre" which coats the foreign substance in a series of layers over time, this explains why all oysters do not contain Pearls. Natural Pearls are found in several varieties such as Salt Water Pearls, Fresh Water Pearls and the rare and much sought after South Sea Pearls. Biwa Pearls are natural Pearls which come from clams in Lake Biwa of Japan, many other pearls that look like these are incorrectly called Biwa Pearls. Natural Pearls are far more expensive than their counterparts and prices of more than a thousand dollars for a single medium to large, good quality Pearl is not uncommon. A necklace made of natural South Sea Pearls can easily be several hundred thousand dollars.
Akoya Pearls produce natural Pearls but are most notably used to develop Cultured pearls in a process started by Mikimoto. Cultured Pearls are also formed naturally in an oyster, but the formation of the pearl is induced by placing a tiny bead into the oyster. This bead is known as the nucleus of a Cultured Pearl. Normally after two to four years the oysters are harvested and the Cultured Pearls are removed, this process of Pearl farming results in most oysters creating a Pearl and the sizes can be controlled by changing the size of the nucleus or the length of time the Pearl is left in the oyster. Cultured Pearl necklaces generally range in price from a few hundred dollars to several thousand dollars.
Imitation or Synthetic Pearls are not real Pearls, however they are still used by some jewelry manufacturers because of the higher costs of natural and Cultured Pearls. Imitation pearls are common in marcasite jewelry and are sometimes set in gold.
SHAPES OF PEARLS
The most common Saltwater Pearl shape is round, it's correct name is an "Akoya" Pearl because it comes from an Akoya oyster. Pearls are readily available in sizes up to about eight and a half millimeters. Akoya oysters also produce other shapes of Pearls. Upon close inspection you will find that round Pearls are seldom perfectly round due to the fact that they form naturally. Baroque Pearls are formed when the nucleus drifts toward the muscle of the oyster where the nacre is distributed unevenly resulting in an off round or Baroque Pearl. "Seed" Pearls as they are commonly referred to, are tiny round Pearls that are less 2.5mm in diameter. Fresh Water Pearls are usually rice shaped with a very rippled surface but they may be round and are often very smooth. Mabe' Pearls are domed shaped Pearls that have flat backs. The Mabe' shape is created when the material that causes the oyster to secrete the nacre gets embedded between the soft tissue of the oyster and the shell. The Pearl is then cut from the oyster with part of the shell attached, hence the flat back. Unlike round Pearls, Mabe' Pearls are common in sizes of 10mm or more and are most popular when set in earrings. Mabe' pearls occur in nature and are also cultured as well by inserting half of a bead against the shell of the oyster.
After Pearls are harvested they are sorted by shape, size, color, and quality. Pearls that are round and have a significant imperfection in one spot will be separated so the imperfection can be cut off leaving a small flat spot, this creates a "three quarter" Pearl known as a Scant Pearl. Scant Pearls and some round Pearls are commonly "half drilled" for use in post earrings or rings. A half-drilled Pearl, as the name implies has a hole drilled from the surface to the center so the pearl may be cemented to a metal post to permanently secure it to the finished piece of jewelry. Un-drilled Pearls are also used for jewelry, they are set with prongs, but most people prefer the clean look of a Pearl set on a post.
A "strand" of Pearls is a set of matched Pearls which are drilled and strung temporarily, several stands of Pearls of similar quality are bound together at one end in what is called a hank. Jewelers will purchase several strands from a hank in order to create whatever length the customer desires. When a Pearl necklace is made, the Pearls are strung on silk thread with a knot between each Pearl. The knot serves several purposes, including keeping the Pearls spaced evenly so they don't scratch each other, and preventing the loss of more than one Pearl if the strand should break. A graduated Pearl necklace is one in which the center of the necklace has the largest Pearl and the sizes of the Pearls get smaller and smaller as you move away from the center of the necklace. Different lengths of Pearls have specific names, they are listed here;
over72".........SAUTOIR (also known as ROPE)
Pearls are available in many different qualities ranging from commercial grades to fine qualities and rare specimens. Currently there is no standard grading system for Pearls like the one used to grade Diamonds. Pearls are graded according to shape, orient, luster, cleanliness, and color. Blemishes on the surface of Pearls may have a large effect the quality and value of a Pearl depending on the size and type of blemishes.
Because pearls are formed in an oyster, well shaped Pearls are rarer and therefore will command higher prices in the marketplace. Orient is the depth, iridescence and translucence of the nacre layering. Luster is the glow or shine created when light travels through the nacre of the Pearl and is different than the light reflected off the surface of a Pearl. Cleanliness refers to the surface markings on a Pearl, the smoother the surface is the higher the value of the Pearl will be. Color is the tone, how strong it is and what color it is will affect the value of a Pearl. Pearls are common in white, pink, gray, or black, but they are also found in other colors. The demand for specific colors varies in different regions of the country and the same is true for sizes. In our area white to slightly pink in 6 to 6.5mm is the most requested type of Pearl.
Akoya Pearls are common up to 8.5 or 9mm in diameter and larger natural Pearls are almost always South Sea Pearls and they are common between 10 and 15mm but have been found in sizes of more than 20mm. The largest Pearls in the world come from the largest and and rarest Pinctada Maxima oysters.
Pearl grades used by many suppliers are shown below for your reference;
EXTRA FINE QUALITY
-minute surface markings
-minute surface markings
-minute surface markings
-medium to light orient
-medium to light luster
-very light orient
-very light luster
Stands of AAA quality Pearls are not readily available in the United States, most high quality pearls are used individually or in small groups in fine pieces of jewelry.
OTHER TERMS / INFORMATION
Pearl is the birthstone for the month of June. Pearls are weighed in a unit of measurement called "momme." "American Cultured Pearls" are Pearls which are farmed in the rivers of Tennessee and its surrounding region. A "Golf Bracelet" is one or several rows of Pearls set in a gold mounting and is the Pearl industry's version of the Diamond tennis bracelet.
Mother of Pearl is the inner shell of an Oyster which has been coated with layers of nacre. Mabe Pearls are formed against the shell and are also known as Blister Pearls.
CARE OF PEARLS
Since Cultured Pearls are made in nature by oysters, they are more sensitive to the elements than other gems. Pearls are organic like Opals and Cameos, while almost all other gems are minerals. Constant exposure to sunlight can dull a Pearls luster, for this reason Pearls are not usually displayed in store windows that receive direct sunlight and the temperatures may exceed one hundred and forty degrees. Pearls are porous so they absorb liquids and should not be immersed in liquids, especially those with color that may stain the Pearls. The natural oils from your skin will enhance the beauty of your Pearls and is a good reason to wear them often. Pearls should be restrung regularly, probably every 18 to 24 months, to keep them in top condition. Pearls should be kept in a pouch or separate compartment by themselves in a jewelry box so that your other jewelry does not scratch them. Pearls should always be put on after cosmetics, hairspray etc.