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White Tahitian Pearl

The Gemstone Pearl

Pearls have been highly valued as gemstones since antiquity, and their allure and beauty has always been magnified by the difficulty of obtaining them in early times. Unlike most other gemstones which are minerals, Pearls are organic and are formed by living organisms. They are generally formed within the soft tissue layer of mollusks such as oysters and mussels. Pearls are composed of calcium carbonate (in the form of Aragonite) and organic conchiolin that build up as concentric layers as they are secreted by their host.
Color White, Blue, Green, Yellow, Orange, Brown, Pink, Purple, Gray, Black, Multicolored
Hardness 2.5 - 4.5
Crystal System Amorphous
Refractive Index 1.52 - 1.69
SG 2.6 - 2.8
Transparency Opaque
Double Refraction .156
Luster Pearly
Cleavage None
Mineral Class Calcium carbonate and conchiolin (organic) combined with water


Though Pearls occur naturally in the wild, their occurrence is very sporadic and limited. Almost all Pearls currently available on the gemstone market are cultured. Cultured Pearls are produced by inserting a foreign substance known as a nucleus within the body of an oyster or mussel, which in turn causes the organism to grow a pearl around the nucleus. Oysters are cultivated and harvested in mass numbers for the purpose of growing Pearls within them.

Pearls come in many different colors, and these are often broken down by variety. One of the most popular forms of Pearls is the Akoya Pearl, which originates from Japan and China. Akoya Pearls occur naturally in white, and are sometimes treated to look black or a very dark blue. A consistent round shape and a mirror- like, almost metallic luster distinguishes Akoya Pearls. Akoya Pearls are bead-nucleated, which accounts for their round shape and sharp luster. In today’s pearl market, smaller sized Akoya Pearls are typically farmed in China, whereas larger sized Akoya Pearls are farmed in Japan. Most people associate Akoya Pearls with Japan. Akoya Pearls are the most popular saltwater pearls.

Exotic Pearls include White South Sea Pearls and Golden South Sea Pearls. White South Sea Pearls usually originate from the western coast of Australia. Golden South Sea pearls originate from the Philippines and Indonesia. South Sea Pearls are noted for their large size and scarcity. Another very popular kind of saltwater Pearl is the Tahitian Pearl, also known as “Black Pearl.” Tahitian Pearls come from the island of Tahiti in the Pacific Ocean and other islands in French Polynesia. They range in color from green to blue, red, gold and black. Introduced to the market in mid-1900, these Pearls continue growing in popularity and prestige.

The most abundant form of Pearl are Freshwater Pearls. Freshwater Pearls come from mussels, and each mussel can produces up to 50 Pearls. (All other pearl varieties come from saltwater oysters which produce only one to three Pearls per oyster). Freshwater Pearls are less desirable than their saltwater counterparts, especially because of their habit of forming in irregular “potato” like shapes. However, with advances in Pearl culturing, Freshwater Pearls have gained a more prominent position amongst higher quality Pearls. In general, no Freshwater Pearl will be perfectly round. This is because they are nucleated with small pieces of tissue, as opposed to round beads. Freshwater Pearls are most distinct because they naturally occur in a variety of colors such as white, peach, pink, purple, and even sometimes a periwinkle blue. Like Akoya Pearls, Freshwater pearls are commonly dyed black, which creates an iridescent effect similar to oil on pavement; i.e. a rainbow of color coats a dark background.

Natural Pearls are rare to come across and seldom used in jewelry. Unless explicitly called “Natural Pearl,” buyers should assume that a Pearl is cultured. When used in jewelry, natural Pearls are almost always used in single-Pearl jewelry pieces. Natural Pearls are expensive due to their rare occurrence and limited availability. Antique Pearl jewelry can also be very valuable because of its authentic designation and historical significance as being natural.

Pearls are typically most valuable when in a perfect round shape. Other significant value factors include luster, color, surface quality, size, and nacre thickness. If the Pearls are strung on a strand, they need to be expertly matched so that the Pearls look consistent. This takes the trained eye of a Pearl professional and can also affect the value of a strand of Pearls. Although Pearls are typically round, they can also be dropped shaped, baroque, semi-round, or free-form. Many of the more freely shaped Pearls are used for pendants or rings that accentuate the unique shape.

There is is no standard grading system for Pearls. This makes purchasing Pearls somewhat of a challenge for a novice. Most companies follow the AAA grading system, or a variation of this system. A buyer should be aware of the description behind whatever grade a Pearl is given. The percentage of blemishing is a good indicator of the quality. Highest quality Pearls should be 95-99% blemish free. There is virtually no such thing as a “perfect” Pearl and buyers should not expect to find one.

Although Pearls are characterized by body color, they also have an “overtone.” Overtone is the word used to describe the glint of a Pearl in various lighting. Overtones are most apparent in saltwater pearls. Although Freshwater pearls have an overtone, it is not as prominent or exact as those found in saltwater pearls. White Akoya Pearls will have overtones in rose, cream and silver. Tahitian Pearls can have an overtone of almost every color. Golden South Sea Pearls will have gold body color with silver, green or rose overtones. White South Sea pearls, like Akoya pearls, have overtones in silver, rose and ivory. Generally a combination of rose and silver is the most sought after overtone for white Pearls.

Pearls are among the most popular gemstones and have been used since antiquity. All colors and types of Pearl are used as gemstones, and they are especially popular as necklaces. Pearls are also extensively used as bracelets, and can also be the center stone in rings, earrings, and pendants. Pendants are often made of non-rounded Pearls such a baroque-shaped Pearls.
Pearl is the birthstone of June.

There are literally hundreds of varieties of Pearls, as well as many names coined by individual dealers. Due to the abundant discoveries, it is often difficult to consolidate these international findings of Pearl species into a decisive list. A comprehensive research on Pearl varieties can be found in German expert Elisabeth Strack’s book, Pearls. (One of the best online resource for Pearl information is www.pearl-guide.com. This forum has information on every aspect of Pearls, including Pearl history and Pearl farming.) The list below contails the most commonly referenced variety names:
  • Abalone Pearl  -   Pearl found in the mollusk haliotis. These Pearls are often an iridescent bluish color and commonly horn-shaped.
  • Akoya Pearl  -  Bead-nucleated Cultured Pearl produced from akoya oysters (pinctada fucata martensii/chemnitzii), primarily in Japan and China, and also from Vietnam, South Korea and Australia.
  • Black Pearl  -   Any Pearl that is dark in color. Black Pearls are usually synonymous with Tahitian Pearls. Black Pearls are often dyed. (See Black Pearls in our resource guide for additional information.)
  • Cortez Pearl  -  Dark Pearl grown in the pinctada maxima and pteria sterna mollusks in Mexico off the Gulf of California. (See Cortez Pearls in our resource guide for additional information.)
  • Cultured Pearl  -   Pearl grown with the influence of human intervention, in which a nucleus material is inserted into an oyster or mussel, and the Pearl forms over this material. (See Cultured Pearls in our resource guide for additional information.)
  • Freshwater Pearl  -  Pearl that grew in a non-saline environment in a freshwater mussel. (See Freshwater Pearls in our resource guide for additional information.)
  • Keshi Pearl  -   Pearl formed when an oyster rejects an implanted nucleus before the culturing process is complete. Keshi pearls are 100% nacre and therefore technically not true pearls. (See Keshi Pearls in our resource guide for additional information.)
  • Mabe Pearl  -  Rounded Pearl that grows attached to the inside of the oyster's shell, rather than within its tissue. (See Mabe Pearls in our resource guide for additional information.)
  • Melo Pearl  -   Rare form of Pearl from Southeast Asia that is formed from a marine snail called melo melo. Although technically not considered a true Pearl as it didn't form within a mollusk, Melo Pearls are often regarded Pearls due to their formation in an organic marine environment and similarity to Pearls. (See Melo Pearls in our resource guide for additional information.)
  • Natural Pearl  -  Pearl that is formed from calcium carbonate secretions that form naturally within a mollusk without any human intervention. This term is distinguished from the more common Cultured Pearls which are produced with human intervention. (See Natural Pearls in our resource guide for additional information.)
  • Oriental Pearl  -   Synonym of Saltwater Pearl.
  • Saltwater Pearl  -  Pearl produced by a mollusk such as an oyster in a body of saltwater such as the ocean. (See Saltwater Pearls in our resource guide for additional information.)
  • Scallop Pearl  -   Form of Pearl produced by any member of the pectinidae (scallop) family. Although technically not considered a true Pearl as it didn't form within a mollusk, Scallop Pearls are often regarded Pearls due to their formation in an organic marine environment and similarity to Pearls. (See Scallop Pearls in our resource guide for additional information.)
  • South Sea Pearl  -  Pearl produced by the pinctada maxima mollusk. South Sea Pearls are highly regarded and cultured in areas throughout the Indian and Pacific Oceans, primarily in Australia, the Philippines, Indonesia and Burma (Myanmar). (See South Sea Pearls in our resource guide for additional information.)
  • Tahitian Pearl  -   Highly regarded type of Pearl produced in the nlack-lipped oyster (pinctada margaritifera), and cultured in the vicinity of the South Pacific Island of Tahiti and other French Polynesian islands. (See Tahitian Pearls in our resource guide for additional information.)

Almost all Pearls sold today are Cultured Pearls, having been grown with the help of humans. The gem trade treats this a normal business practice, and this has become the standard. Natural and Cultured Pearls can be distinguished using x-ray equipment that can examine the nucleus of a Pearl.

Pearls are commonly dyed to give them a more valuable color and increase their overtone. The most prevalent colors they are dyed are black and dark blue. Imitation Pearls are very easily created and are widely available. They are often sold as inexpensive jewelry pieces, but their quality and iridescence are usually lacking when compared to natural Pearls. They can usually be easily distinguished both by x-ray and microscope, and experts can even determine their difference by just look and feel.

Most Saltwater Pearl culturing takes place in the Indian and South Pacific Oceans. Pearls are primarily cultured in China, Japan, the Philippines, Indonesia, Burma (Myanmar) Australia, and in French Polynesia (especially Tahiti). Freshwater Pearls are cultured primarily in China and Japan and in several states in the U.S.

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