There are four major different types of pearls: Freshwater, Akoya, South Sea and Tahitian. Each pearl type is unique with the color, size and shape.
Freshwater cultured pearls are cultivated in a freshwater mollusk from a lake, river or pond. Mostly from China, they are also farmed in Japan, the US and other locations. They are similar in look to the Akoya pearls.
Akoya cultured pearls are generally found in several varieties of saltwater mollusks in the waters around Japan and China.Akoya pearls are one of the most popular pearl type for their luster and beauty.
South sea cultured pearls are ranging in hues of white, gold, silver, cream and champagne, these cultured pearls are quite large and are cultivated in the white-lip oyster. South sea pearls are harder to cultivate but are larger pearls that are also more expensive due to a lengthy three-year maturation time and very limited production. These pearls can have either a white or black body color. Black south sea pearls are incredibly beautiful but extremely rare.
Tahitian cultured pearls are cultivated in the black-lip oyster found in French Polynesia, and producing pearls in natural tints of black, silver, gray, green, orange, gold, blue and purple. Black Tahitian pearl is darker and larger. They are very unique and expensive because of the complicated cultivation process. Besides,
Biwa Pearl is cultivated in a freshwater mussel in Biwa, Japan.
Baroque is a cultured pearl that is asymmetrical and free form in shape.
Conch pearl is similar in color to pink coral, these pearls are produced by a conch, a saltwater mollusk from tropical waters.
Abalone pearl is a naturally cultivated pearl from an abalone, which is a univalve mollusk.
Imitation pearls are man- or machine-made pearls. Unless a pearl is created by an oyster, it is an imitation. Shell, irregular beads, plastic, glass, wax and fish scale are the most common substances used in the manufacture of imitation pearls.
Keshii pearl also known as a seed pearl, is a non-nucleated pearl produced accidentally as a by-product of the cultivating process, and consequently not considered a natural pearl.
Mabe pearl is a dome-shaped cultured pearl cultivated on the inner shell of a mollusk rather than in its body. Mabe pearls generally have a bigger diameter and are ideal for larger jewelry.

Pearl Quality

Pearls are classified by origin, then their quality is graded by type, size, shape, nacre thickness, color, luster, surface clarity and matching. Grading is relative to the best attainable quality for the type. These factors are weighted to arrive at a final grade to determine a pearl's quality and worth.

Size: Limited by the mollusk used in cultivation, size is a very significant factor in valuing pearls. For each pearl type, there is a different average size. Larger mollusks create larger pearls, therefore South sea and Tahitian pearls are larger than Akoya and Freshwater pearls. However, a pearl of large size will likely to be irregular in shape.
Freshwater pearls range from 5-8.5 mm in diameter for best quality.
Akoya pearls range from 6-8 mm in diameter, 8 mm being large.
Average South Sea pearls range from 11-13mm in diameter.
Black Tahitian pearl, known as the Queen of Pearls, ranges from 11-12mm in diameter.

Shape: Refers to the symmetry and form of the pearl. The most popular pearl shape is perfectly round. Round pearls are the rarest and most highly prized. So rare are round pearls that round 5% of a pearl farm's harvest will be even or round. However, there are other pearl shapes that are popular too, such as rice, tear drop, coin, barrel, button (also known as the mabe shape), ringed (ridged) and symmetrical pearls. More irregular shapes fall under the baroque shape category. Some of them are graded as fancy shaped pearls according to their symmetry and balance. Symmetrical pearls of other pleasing shapes are rated for symmetry, but priced according to a different scale from rounds.

Nacre: the single most important factor in the beauty and durability of the pearl. Nacre is the substance that gives pearls their luster and beauty. Some pearls with thin nacre have high luster and are free of blemishes, because they have been left in the water for only a brief time. This thin surface will soon be damaged by normal wear, and may chip or peal around the drill hole. The thicker and smoother the nacre are, the higher the quality of pearl.

Luster: the brightness or reflectivity of the pearl, is produced by light entering the pearl and reflecting back through the layers of nacre. Luster is the mirror-like finish on the pearl surface. The very top pearls have a metallic luster, while fine pearls have a sub-metallic luster but still reflect objects sharply on the surface. Low-luster pearls display very little if any reflectivity. The larger pearl contain more nacre, or layers, and the pearl becomes more lustrous. The quality of the luster is directly related to how even and smooth the layers of nacre are.

Color is described by the base color of the pearl, called body color, and any additional colors that may be overlaying the base color, called overtone. Pearls come in a wide range of colors such as white, rose, cream, black, grey, gold, silver, green, blue, and purple. Different pearl types come in different colors.
Freshwater pearls are usually white, pink, peach, lavender, plum, purple and tangerine. The most popular shade of freshwater pearls is white with rose undertones.
Akoya pearls are usually white, cream, rose, gold and blue gray.
Southsea pearls come in colors as white, gold, silver, cream and champagne. The white color has silver or rose undertones.
Tahitian pearls are black, gray, silver, green, orange, gold, blue and purple. The black color has green or pink undertones.
Color does not affect the price of pearls as it is mostly a matter of taste - when choosing a color a general guideline is skin tone. Many women with fair or light colored skin feel pink overtones look best. While women with dark skin or that tan easily find black or cream overtones look best.

Surface texture refers to blemishes or spotting on the surface of the pearl. They are graded by their size, type, number, location and visibility. When picking out a pearl necklace, the pearl surface is the most important thing to look at. Like diamonds, there are rarely perfect pearls, but the premium pearls are those that have very little imperfections, such as spots or bumps.
Non-damaging pearl blemishes include spots, bumps, pits, and wrinkles which don't harm the pearl jewelry and won't make the pearls weaker and more fragile, but they can affect the price and value of the pearl necklace. Damaging blemishes include cracks, holes or chips. Those blemishes may worsen and affect the durability of a pearl. When buying pearls, it's important to find ones that are lustrous enough to last you a long time, because the nacre will wear off over time from friction due to rubbing against clothing and skin.
A good quality pearl will have few blemishes or marks. With pearls the cleaner the surface the more valuable it will be. The deeper the luster, the higher the quality of pearl is produced.

Matching refers to pairs or strands, and addresses uniformity of color, luster, shape, spotting and graduation. If colors are intentionally mixed, it refers to the attractiveness of the combination. Each pearl in a strand has been selected to be placed between its neighbor on each side, and there should be no noticeable difference between pearls that are side-by-side. Even in "uniform" strands, there will be gradation in size from the center pearl to those at the ends.

Orient - play of color, or iridescence seeming to move about the surface of some pearls. It is a rare component, more often seen on irregular surfaces. A perfectly blemish-free pearl is usually not drilled, but rather is mounted in prongs or glued in place. If the pearl is perfectly "clean" except for one blemish, a drill hole will be placed through the blemish. Pearl beads are drilled though one, or sometimes two blemishes, to yield the best quality possible.

Purchase Guide

Pearl necklaces are a favorite among women of all cultures. Their distinctive glow that seems to hover right above the surface charmed and enchanted girls and ladies of all ages throughout history. When buying pearl jewelry, there are a few things to consider: color, size, luster, surface and shape.
As you are choosing color, keep in mind that each type of pearl has different colors. Size of the pearls depends on the type of pearls. Luster shows the quality of the pearl. When looking at the luster of a pearl necklace, check out the surface of the pearls. There is rarely a perfect pearl with a smooth surface, but you can look for pearls that are near-perfect. Blemishes that may appear, but not are non-damaging include spots, bumps, pits, and wrinkles. Those flaws may worsen and ruin the pearl.
When choosing a pearl necklace, keep in mind that there are six types of pearl necklaces; collar (10" ~ 13"), choker (16" ~ 18"), princess (17"~ 20"), matinee (20" ~ 24"), opera (28" ~ 34") and rope (45" and up). When shopping for pearls, look for ones that are round, smooth, and shiny.
Wholesale pearls will save you a lot of money. Pearls in retail outlets often cost multiple times the wholesale price and other costs of running a retail store. It's important to get a good grade pearl to ensure that you can enjoy it for many years to come.
Faux pearl jewelry are a great alternative to expensive real pearls if you just need something to bring out extra beauty for a special occasion.

Pearl Care

Protect pearls from chemicals, abrasion or beauty products. Cultured pearls are relatively soft compared to other gemstones and precious metals. So it is important to take special care of your pearls to ensure they will remain bright and beautiful for generations to come. Most dust contains much harder quartz particles. Thus, pearls are easily scratched by careless cleaning. Keep pearls in their own soft case or bag, and wait to put them on until your hair, make-up and perfume have all been applied. After wearing them against the skin, wipe pearls gently with a very soft, damp cloth before returning them to their secure haven to keep it lustrous. As pearls seem to benefit from exposure to the light, remember to wear them often, as the absorption of skin oils adds to their luster and life! Pearls that have been stored in a safe deposit box for long periods may have yellowed.
If you wear your pearls often, it is best to have them re-strung about once every other year to prevent strand breakage. You can use silk thread or nylon thread. Make sure that the string is knotted tightly between each pearl to prevent all the pearls in a strand from falling off and from rubbing against each other.