A Pearl is a hard, rounded object produced by certain mollusks, primarily oysters. Pearl is valued as a gemstone and is cultivated or harvested for jeweller.

Pearls are formed inside the shell of certain bivalve mollusks. As a response to an irritating object inside its shell, the mollusk will deposit layers of calcium carbonate in the form of the minerals or calcite (both crystalline forms of calcium carbonate) held together by an organic horn-like compound called conchiolin. This combination of calcium carbonate and conchiolin is called nacre, or as most know it, mother-of-pearl.

The unique luster of pearls depends upon the reflection and refraction of light from the translucent layers and is finer in proportion as the layers become thinner and more numerous. The iridescence that some pearls display is caused by the overlapping of successive layers, which breaks up light falling on the surface. Pearls are usually white, sometimes with a creamy or pinkish tinge, but may be tinted with yellow, green, blue, brown, or black. Black pearls were highly valued because of their rarity.

The History of the Pearl:

Before the beginning of the 20th Century, pearl hunting was the most common way of harvesting pearls. Divers manually pulled oysters from ocean floors and river bottoms and checked them individually for pearls. Not all natural oysters produce pearls, however. In fact, in a haul of three tonnes, only three or four oysters will produce perfect pearls.

Now, however, almost all pearls used for jewelry are cultured by planting a core or nucleus into pearl oysters. The pearls are usually harvested three years after the planting, but it can take up to as long as six years before a pearl is produced. This mariculture process was first developed by Kokichi Mikimoto in japan, who was granted a patent for the process in 1896.

The nucleus is generally a polished bead made from mussel shell. Along with a small scrap of mantle tissue from another oyster to serve as an irritant, it is surgically implanted near the oyster's genitals. Oysters 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 three years of growth.

The original Japanese cultured pearls, known as Akoya pearls, are produced by a species of small oysters no bigger than 6 to 7 cm in size, hence Japanese pearls larger than 10 mm in diameter are extremely rare and highly priced. In the past couple of decades, cultured pearls have been produced with larger oysters in the south Pacific and Indian Ocean.

One of the largest pearl-bearing oysters is the Pinctada maxima, which is roughly the size of a dinner plate. South Sea pearls are characterized by their large size and silvery color. Sizes up to 14 mm in diameter are not uncommon. Australia is one of the most important sources of South Sea pearls. Tahitian pearls (also referred to as Titian pearls) are also another South Sea pearl.

In the 1990's, Japanese pearl producers also invested in producing cultured pearls with freshwater mussels in the region of Shanghai, China, and in Fiji. Freshwater pearls are characterized by the reflection of rainbow colors in the luster. Cultured pearls are also produced using abalone.

The Value of Pearls:

The value of the pearls in jewelry is determined by a combination of the luster, color, size, lack of surface flaw and symmetry that are appropriate for the type of pearl under consideration. Among those attributes, luster is the most important differentiators of pearl quality according to jewelers. All factors being equal, however, the larger the pearl the more valuable it is. Large perfectly round pearls are rare and highly valued. Teardrop-shaped pearls are often used in pendants. Irregular shaped pearls are often used in necklaces.

Pearls come in eight basic shapes, round, semi-round, button, drop, pear, oval, baroque, and ringed. Perfectly round pearls are the rarest and most expensive, and are generally used in necklaces, or strings of pearls. Semi-rounds are also used in necklaces or in pieces where the shape of the pearl can be disguised to look like it is a perfectly round pearl. Button pearls are like a slightly flattened round pearl and can also make a necklace, but are more often used in single pendants or earring where the back half of the pearl is covered, making it look like a larger, round pearl.

Drop and pear shaped pearls are sometimes referred to as teardrop pearls and are most often seen in earrings, pendants, or as a center pearl in a necklace. Baroque pearls have a different appeal to them than more standard shapes because they are often highly irregular and make unique and interesting shapes. They are also commonly seen in necklaces. Ringed pearls are characterized by concentric ridges, or rings, around the body of the pearl.

In general, cultivated pearls are less valuable than natural pearls, and imitation pearls are the least expensive. One way that jewelers can determine whether a pearl is cultivated or natural is by x-raying the pearl. If the grit in the centre of the pearl is a perfect sphere, then the jeweller knows it is cultivated. This is because when the cultivators insert the grit, (usually a polished piece of mussel shell), it is always perfectly round, so as to produce a more expensive, perfectly round pearl. If the centre is not perfectly round, the jeweller recognizes that it is genuine, and gives it a higher value. Imitation pearls are much easier to identify by jewelers. Some imitation pearls are simply made of mother-of-pearl, coral or conch or conch, while others are made from glass and are coated with a solution containing fish scales called essence d'Orient. Although imitation pearls look the part, they do not have the same weight or smoothness as real pearls, and their luster will also dim greatly.

There is also a unique way of naming pearl necklaces. While most other necklaces are simply referred to by their physical measurement, strings of pearls have their own set of names that characterize the pearls based on where they hang when worn around the neck. A collar will sit directly against the throat and not hang down the neck at all, they are often made up of multiple strands of pearls. Pearl chokers nestle just at the base of the neck. The size called a princess comes down to or just below the collarbone. A matinee of pearls falls just above the breasts. An opera will be long enough to reach the breastbone or sternum of the wearer, and longer still, a pearl rope is any length that falls down further than an opera.

Necklaces can also be classified as uniform, where all the pearls are the same size, graduated, where the pearls are arranged in size from large in the centre to smaller at the ends, or tin cup, where pearls are generally the same size, but separated by lengths of chain.

There are real pearls and then there are fake (faux) pearls...

If you are buying pearls, you may be able to identify fake pearls by their name: simulated, faux, glass, plastic, resin, artificial, manmade. Genuine pearls come in a variety of 'flavors'.

There are natural pearls and cultured pearls. Real pearls may come from freshwater or saltwater and from a variety of molluscs (not just oysters). To further confuse things, there are also shell pearls and genuine pearls, which have had treatments applied to them, such as coatings or faceting.

Before you buy or sell pearls, you need to know whether they are real or not. Here are some ways to tell them apart. The following are "tests" which can help you discern the quality of the pearls you have purchased.

Destruction Test (not recommended)
X-Ray
The Tooth Test
The Sun Test
Other Visual Clues
Density
Hole Characteristics
The Settings
Destruction:

If you cut a pearl open, you will see its true nature. Natural pearls are comprised of layer upon layer of nacre. Cultured pearls have a shell (mother-of-pearl) core covered with a thin layer of nacre (generally no more than half a millimeter, usually much thinner). Fake pearls have a core with one or more layers of coating applied to them, which tends to flake away from the core upon cutting. Cutting a pearl down the middle reveals the nature of its drill hole, if present. Of course, you need to be able to tell pearl-colored glass from shell in order to do this test (plastic and resin are easier to discern). Also, you'll destroy the pearl during this process.

X-Ray:

If you really need to know whether or not your pearls are real or fake or whether they are natural or cultured, you are going to have to pay someone, preferably a certified gemologist, to x-ray them for you. An x-ray will show the inside of the pearl, including variations in its density, the presence or absence of a parasite that might have caused the formation of a natural pearl, and the characteristic shapes of drill holes, if present.

The Tooth Test:

First, the "Tooth Test" while hailed by many as a surefire way to know if pearls are real or fake is not very reliable.

To use the tooth test, you rub the surface of the pearl over your teeth (make sure the pearls are clean). In general, a real pearl feels gritty while a (fake) faux pearl feels smooth.

The premise behind the test is valid...

Real pearls are made up of many layers of nacre that are deposited like sand on a beach -the slight irregularities in the nacre can produce a gritty or bumpy feeling against the teeth.

On the other hand, many synthetic nacres are applied smoothly onto perfectly smooth beads and these pearls would feel smooth against the teeth. The test is pretty good for distinguishing rare natural pearls from glass pearls, but it isn't as good at identifying cultured pearls, which have fewer layers of nacre and may feel more smooth.

If the pearls are dyed, the dye can fill in natural depressions in the pearls, making them feel smooth. Also, some synthetic pearls are made to look and feel like real pearls.

Mabe pearls may have a protective coating applied to them, which makes them smooth even though they may be genuine. The formulation of the nacre can closely resemble that of real pearls. The nacre could be applied to a natural base, like a shell bead, making this test completely unreliable.

The tooth test is a nice test, but don't base your judgement of authenticity on this test alone.

The Sun Test:

This is one of the easier and less costly tests to perform. You could perform this test outside in natural sun or under a very bright light. Unless they are very expensive (genuine pearls) they won't be perfectly matched under the sun.

In natural sunlight, you will be able to see variations in iridescence (orient) and color. If the pearls are perfectly matched for color and overtones, they are most probably fake.

If you are buying pearls from a seller who offers pearls that are perfectly matched, the cost of such pearls will be extremely high (into the thousands). These are pearls that are worth spending the extra money to have appraised by an independent gemologist.

Visual Test:

Fake (faux) look 'flat' in comparison to the real thing. There are exceptions, of course, with beautiful simulated pearls made by Swarovski and other manufacturers. Real pearls tend not to be perfect and may display bands in their nacre, bumps, ridges, or pits. They will vary in size and shape from one to another.

Genuine Pearls may have concentric ridged circles around them, which many buyers may take for marks from molding of a fake (which is seen in the exact middle of all the pearls on strands of some faux pearls).

Real Pearls come in many shapes, but they tend not to be perfectly round, so a "perfect sphere" should be suspect. Expensive genuine pearls may be round, but you will have other clues to help you make a determination. Some fakes are made to look irregular, and glass pearls often have flattened ends or slightly oval shapes.

In addition to visual clues, genuine pearls tend to warm to the skin much faster than glass pearls.

Drill Holes:

Real pearls tend to be drilled from both sides, to meet in the center. If you could see the cross section of the pearl, the hole may appear wider at the outside edge of the pearl than at the center.

Holes of real pearls tend to be as small as possible (with some exceptions), since the weight of a pearl affects its price (a larger hole translates into less weight and lower value).

Inexpensive real pearls may be lower in cost because the drill holes are not completely straight. Fake pearls often have larger, possibly straighter holes than real pearls. Some fakes are made to have smaller holes, so that they can be knotted like their genuine counterparts.

The Setting:

In a finished necklace or bracelet, real pearls are more likely to have knots between each pearl than faux pearls. Real pearls are more likely to have settings of gold, silver, or platinum than faux pearls.

You can examine clasps for stamps or engravings in the metal. Clasps tend to have safety mechanisms, like fish hooks, but some real pearls are sold with other types of clasps such as those which secure "hand in glove" (slide clasp) and the clasp is usualy made of 10KT., 14KT., 18KT. or Platinum.

Brand Names:

In the "World of Pearls" brand name does matter. Buyer's trust names such as Akoya and Mikimoto as names they can trust. However, when a brand name is not attached to the pearl or pearls you're contemplating purchasing, following the above "tests" (while not fool proof) can assist you in knowing the real thing from "faux".

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