Monday, August 10, 2009

Pearls: Natural Pearls and Cultured Pearls

Since I launched my new Etsy shop where I introduce my new Bridal line using a lot of high quality pearls while having affordable prices by making more simple pieces I hear a lot of comments from people stating that I probably use non-natural pearls because real pearls should be way more expensive. So here is some answers to those questions.

Natural pearls vs cultured pearls
A "natural pearl" is one that forms without any human intervention at all, in the wild, and is very rare. Many hundreds of pearl oysters or pearl mussels have to be gathered and opened, and thus killed, in order to find even one wild pearl, and for many centuries that was the only way pearls were obtained. This was the main reason why pearls fetched such extraordinary prices in the past. A cultured pearl, on the other hand, is one that has been formed with human intervention on a pearl farm. The vast majority of pearls on the market today are cultured pearls.
A well equipped gem testing laboratory is able to distinguish natural pearls from cultured pearls by using a gemological x-ray in order to examine the center of a pearl. With an x-ray it is possible to see the growth rings of the pearl, where the layers of calcium carbonate are separated by thin layers of conchiolin. The differentiation of natural pearls from tissue-nucleated cultured pearls can be very difficult without the use of this x-ray technique.

Do natural pearls exist nowadays?

Quality natural pearls are very rare jewels. The actual value of a natural pearl is determined in the same way as it would be for other "precious" gems. The valuation factors include size, shape, quality of surface, orient and luster.
Single natural pearls are often sold as a collector's item, or set as centerpieces in unique jewelry. Very few matched strands of natural pearls exist, and those that do often sell for hundreds of thousands of dollars.
Previously, natural pearls were found in many parts of the world. Present day natural pearling is confined mostly to seas off Bahrain. Australia also has one of the world's last remaining fleets of pearl diving ships. Australian pearl divers dive for south sea pearl oysters to be used in the cultured south sea pearl industry. The catch of pearl oysters is similar to the numbers of oysters taken during the natural pearl days. Hence significant numbers of natural pearls are still found in the Australian Indian Ocean waters from wild oysters.

How to distinguish between cultured pearls and fake pearls?

The method of testing for imitations is to rub the pearl against the surface of a front tooth. Imitation pearls are completely smooth, but natural and cultured pearls are composed of nacre platelets, which feel slightly gritty.

Definition of pearl

Almost any shelled mollusk can produce some kind of "pearl" when an irritating microscopic object becomes trapped within the mollusk's mantle folds, but the great majority of these "pearls" are not valued as gemstones. Nacreous pearls, the best-known and most commercially-significant pearls, are primarily produced by two groups of mollusks bivalves or clams. A nacreous pearl is made from layers of nacre, by the same living process as is used in the secretion of the mother of pearl which lines the shell.

Fresh water and sea water pearls

One family of nacreous pearl bivalves, the pearl oysters, lives in the sea while the other, very different group of bivalves lives in freshwater; these are the river mussels such as the freshwater pearl mussel. Natural freshwater pearls form in various species of freshwater mussels, family Unionidae, which live in lakes, rivers, ponds and other bodies of fresh water. These freshwater pearl mussels occur not only in hotter climates, but also in colder more temperate areas such as Scotland: see the freshwater pearl mussel. However, most freshwater cultured pearls sold today come from China. In addition, pearls (especially cultured freshwater pearls) can be dyed yellow, green, blue, brown, pink, purple, or black
Saltwater pearls can grow in several species of marine pearl oysters in the family Pteriidae which live in oceans. Saltwater pearl oysters are usually cultivated in protected lagoons or volcanic atolls.

The development of pearl farming

Today, almost all pearls used for jewelry are cultured by planting a core or nucleus into pearl oysters. The pearls are usually harvested after one year for akoya, 2–4 years for Tahitian and South Sea, and 2–7 years for freshwater. The nucleus is generally a polished bead made from freshwater mussel shell. Along with a small piece of mantle tissue from another mollusk to serve as a catalyst for the pearl sac, it is surgically implanted into the gonad (reproductive organ) of a saltwater mollusk. In freshwater perliculture, only the piece of tissue is used in most cases, and is inserted into the fleshy mantle of the host mussel. South Sea and Tahitian pearl oysters, also known as Pinctada maxima and Pinctada margaritifera, which survive the subsequent surgery to remove the finished pearl, are often implanted with a new, larger nucleus as part of the same procedure and then returned to the water for another 2–3 years of growth.
The original Japanese cultured pearls, known as akoya pearls, are produced by a species of small pearl oyster, Pinctada fucata martensii, which is no bigger than 6 to 8 cm in size, hence akoya pearls larger than 10 mm in diameter are extremely rare and highly prized. Today, a hybrid mollusk is used in both Japan and China in the production of akoya pearls. It is a cross between the original Japanese species, and the Chinese species Pinctada chemnitzii.

Recent pearl production

China has recently overtaken Japan in akoya pearl production. Japan has all but ceased its production of akoya pearls smaller than 8 mm. Japan maintains its status as a pearl processing center, however, and imports the majority of Chinese akoya pearl production. These pearls are then processed (often simply matched and sorted), relabeled as product of Japan, and exported.
In the past couple of decades, cultured pearls have been produced using larger oysters in the south Pacific and Indian Ocean. The largest pearl oyster is the Pinctada maxima, which is roughly the size of a dinner plate. South Sea pearls are characterized by their large size and warm luster. Sizes up to 14 mm in diameter are not uncommon. South Sea pearls are primarily produced in Australia, Indonesia and the Philippines.