Cultured Pearls – Varieties, Quality & Care

Varieties of Cultured Pearls

Akoya Cultured Pearls
Kingoff's Jewelers | Akoya PearlsAkoya pearls are the classic white pearl and typically have the highest luster and greatest shine of all cultured pearls.

The Akoya pearl is the most popular pearl type. They are cultured in saltwater oysters from Japan. These pearls are popular for their luster and beauty.

Depending on the size of the oyster, the size of the pearl may vary between 2mm-10mm. The pearls’ color ranges from cream, white, rose and gold to blue-gray in body color and they typically have a rose, cream or ivory overtone.

The Akoya pearl can look very similar to the round freshwater pearl, but compared side-by-side, the differences are obvious. The Akoya pearl is generally larger, smoother, rounder and more lustrous than a freshwater pearl.

Akoya pearls are the classic cultured pearls of Japan. They are the most lustrous of all pearls found anywhere in the world. In recent years, China has been successful in producing Akoya pearls within their own waters.

South Sea Cultured Pearls
Kingoff's Jewelers | Southsea PearlsThe South Sea pearls are large in size and are produced by much larger oysters in the warm waters of the South Seas, in Australia, Indonesia and the Philippines. Most of the pearls are more than 10mm in size. The color of the South Sea pearls is determined by different oyster types.

South Sea pearls are also the most valued pearl on the market, due to their rarity and thick layers of nacre.

There are two reasons that account for this.  The rarity of a pearl of such size and high luster is due to the difficulty in gathering acceptable quantities from these oysters.  It is also due to the sensitivity of the culturing process.

South Sea cultured pearls are the rarest and most extraordinary pearl you will find in jewelry.

Black South Sea or Tahitian Cultured Pearls
Kingoff's Jewelers | Tahitian PearlsTahitian pearls are from the warm waters of the South Seas of Tahiti and Okinawa.  The Black Tahitian pearl is naturally dark and large, typically 9mm – 16mm. They are unique and prized because of the complicated cultivation process.

Specifically, the natural black color of the Tahitian pearl comes from the black-lipped variety of oyster, which reaches a foot or more in diameter, and produces very large pearls.

The volcanic islands of Tahiti & this region, with their mixture of nutrient-rich ocean water and warm lagoons, create an ideal environment for this type of oyster. It is the only place in the world where the Tahitian pearl can be found.

Though traditionally called “black,” these pearls range in color from metallic silver to the color of pencil graphite with gray, silver, green, blue or purple overtones. It may take a dozen harvest years to collect enough black pearls that match in size, shape and color to create one necklace.

Tahitian pearls are slightly smaller than the South Sea pearl, on average, but larger than the Akoya.

Freshwater Cultured Pearls
Kingoff's Jewelers | Freshwater PearlsThese pearls are cultured mostly in the lakes and rivers of China.

As many as 10 to 14 pearls can be cultured in one oyster, while the Akoya, South Sea & Tahitian oysters can only culture one pearl at a time.

In addition, the Akoya, South Sea, and Tahitian pearls are all cultured using a bead nucleus, which is inserted into the oyster in a surgical procedure which is referred to as “grafting.”  The freshwater cultured pearl is developed using a tissue nucleus which tends to dissolve during the growth process.

Because these pearls do not start with the large round bead, they can grow in a variety of shapes, including round, drop, button, oval and freeform.

In the 1980’s we were familiar with Freshwater Cultured pearls which were  shaped like grains of rice or oval-shaped. However with today’s technology the Chinese have been able to develop pearls of much better shape and quality.

Keshi Cultured Pearls

Kingoff's Jewelres | Keshi Cultured PearlsKeshi pearls are formed when the oyster rejects and spits out the implanted nucleus bead before the culturing process is complete. What is left in the oyster is an empty pearl sac, which eventually produces pearls without a nucleus.

Keshi may form in either saltwater or freshwater oysters. They are generally small in size and, because there was no nucleus to guide the ultimate shaping of the pearl, their shapes vary widely.

Keshi come in a wide variety of colors, and tend to have high luster.

Because the implanted nucleus of the pearl has been expelled by the oyster, the resulting Keshi pearl is 100% nacre. The fact that Keshi pearls are solid nacre does not, however, give them the classification of natural pearls. This is because Keshi are a bi-product of the culturing process, not a natural occurrence.

Six Factors of Pearl Quality

Nacre is the natural substance that a mussel or oyster secretes to protect its sensitive flesh from irritants such as sand, shell fragments or implanted beads.

This nacre is the same iridescent material that lines the inner surface of the oyster shells, aptly named mother-of-pearl.

As a general rule, the thicker the nacre, the higher quality the pearl is.


Luster is the quality of a pearl which shows its mirror-like reflection and surface brilliance. It is the pearls’ glow. The luster of good quality pearls should be bright.

Found on the very surface, luster is measured by the sharpness and brilliance of the reflection.

A good quality pearl captures light well and reflects it back to the observer.

You should be able to see your reflection clearly on the surface of a good pearl. Pearls appearing too white, dull or chalky are not of high quality.


Pearls develop in all shapes, especially freshwater and Tahitian pearls.

They can be round, semi-round, drop, oval, half-rounded, semi-baroque and baroque shapes.

The general rule of thumb is, the rounder a pearl is, the better the quality, assuming all other factors are the same.

A perfectly round pearl is very rare. Other shapes that are not symmetrical in shape can be lustrous and appealing. However, they usually will cost less than round pearls.


Pearls come in a variety of colors, from white to black and every shade in between.

The color of a pearl is a combination of two components: basic body color and overtone.

The body color of a white pearl may appear white, pink, cream, champagne, aqua, golden, green or black.

An overtone is the color that overlies the body color, resulting from the layers of the nacre, and may be seen under different angles of the light.

Typical overtones are rose, pink or silver. Every pearl developed appears with a different color combination, which makes it truly unique from other pearls. Color itself is not the basis in grading pearls rather it is color intensity.  A good quality pearl possesses a deep and equal overtone while a bad one possesses the opposite.


Measuring the size of a pearl basically means measuring the diameter of the pearl expressed in millimeters.

Tiny seed pearls can be smaller than 1 mm, while South Sea pearls as large as 20 mm have been found.

If all other quality factors are equal, the value of the pearl rises gradually with size.

Round and off round pearls are measured by the shortest diameter.  All pearls in other shapes are measured along two diameters (the longest and second longest).

It is important to remember, that size alone is not enough to tell the quality of the pearl.

Caring for Cultured Pearls

Pearls are organic gemstones that are vulnerable to acid, alkaline and different humidity levels.

If substances such as cosmetics, hair spray, or perfume adhere to your jewels, they will lose their radiance, absorbing dirt and dust and causing alteration or loss of color.

Perspiration can also harm your pearls. It will dull their beautiful luster. Therefore, after wearing them, they should be wiped with a damp (not wet) soft cloth.

Be careful not to dip pearls in water or wear them while bathing, as water can weaken the silk thread.

Do not leave them in direct sunlight or expose them to high temperatures.

The golden rule with pearls…”They should be the very last thing you put on and the first thing you take off.”


Most cultured pearl necklaces are strung on silk thread for both strength and beauty.

However, if that string stretches or loosens, it may break suddenly.

Even if you don´t wear your pearls often, we recommend that you have them inspected every year.

Over time, pearls do change in appearance. However, if you take care of them and follow these simple guidelines, your pearls should be enjoyed for generations.


When storing them, always fasten the clasp and pin. This will prevent them from becoming tangled. Also, you should either lay your pearls out in separate compartments in a jewelry box or store them in individual pouches. This will help keep them from being scratched by other jewelry.

Do not store your pearl jewelry in a safety deposit box for long periods of time, since this may cause the pearls to dehydrate.  It is recommended to take the pearls out of such boxes frequently. Pearls need air!