The pearl is unique among precious stones—it is the only one to form inside a living thing. At Katarina, we love this sea-grown gem's natural beauty, from bright white freshwater pearls to the alluring silver tones of the Tahitian pearl. Pearls have been connected to love relationships throughout history and are traditional gifts for the twelfth and thirtieth wedding anniversaries.

How Pearls Are Formed

Pearls form when a small foreign body lodges inside a mollusk such as an oyster. Over time the oyster coats the irritant in many layers of natural minerals and proteins. These layers are called nacre, pronounced NAY-kur. It is the nacre that gives pearls their beautiful luster and color.

Cultured vs. Natural

The foreign body that forms the core of a pearl can be naturally occurring or implanted in the oyster to cause it to form pearls. Natural pearls are extremely rare most pearls sold today are cultured. Pearl farmers implant a tiny bead into the oyster and the oyster coats the bead in nacre, just as it would if the bead were deposited there by nature.

The only reliable way to tell a cultured pearl from a natural pearl is through x-ray studies.


There is no industry-wide standardized grading for pearls as there is for diamonds. Individual producers and sellers may use letter grading systems such as A/B/C/D, with A being the highest, or AAA/AA/A, with AAA being the highest. But again, these systems have not been accepted by the industry as a whole. See below for discussion of each of the properties that affect value. We encourage you to read all our pearl education materials and learn more about the differing qualities of each pearl type. Please contact us if you have any additional questions. Katarina ensures that the pearls we offer meet our quality standards.


As an organic product, no two pearls are alike, so pearl valuation can seem somewhat subjective. Six factors influence the value of a pearl: luster, nacre, surface texture, shape, size and color. All these factors interact in determining value. For example, round pearls are typically more valuable than off-round pearls. But an off-round pearl with excellent luster can be more valuable than a round pearl with thinner nacre and less luster.


Luster is the pearl's most important feature. Luster refers to the reflection of light off the many layers of calcium carbonate crystals in the pearl's nacre. Pearls with high luster are quite reflective—almost mirror-like. Orient, from the Latin for "the rising of the sun," is a quality related to luster. It names the iridescence or "rainbow" effect common on the surface of a quality pearl, caused by the refraction of light through the layers of nacre.


Nacre affects luster and the durability of the pearl. The thicker the nacre, the greater luster the pearl will have and the stronger it will be. South Sea and Tahitian pearls tend to have thicker nacre than Akoya and freshwater pearls.

  The most common pearl colors are white, cream, yellow, pink, silver or black. Many pearls have a trace of secondary color, referred to as overtone, which is seen when light reflects at certain angles off the pearl's nacre. Overtones can be just about any color of the rainbow. The choice of pearl color is a matter of personal preference and what colors will best complement the wearer's complexion.

Pearl shapes fall into three major categories: round, off-round, and baroque. Round pearls are the rarest and most sought-after. Akoya, Tahitian, and South Sea pearls tend to be the roundest.
The off-round category encompasses a wide variety of shapes, from the slightly asymmetrical pearl that appears round to the unaided eye, to pearls that are coin- or barrel-shaped. Although these pearls are not spherical, they are uniformly shaped and proportioned.
Coin-shaped pearls result from implanting a round, flat form—instead of a spherical bead—in the oyster. Virtually all coin-shaped pearls are cultured; natural coin-shaped pearls are few and far between, and priced accordingly. To judge the quality of a cultured coin-shaped pearl, hold it up to the light. The nacre should be thick enough that you cannot detect the implant inside the pearl.
Off-round pearls that are hemispherical in shape are called mabe (MAH-bay). These pearls have one flat side and one dome-shaped side
Pearls that are completely asymmetrical are called baroque. Shape is a matter of personal preference; some people appreciate the unique beauty of baroque pearls, although sales indicate that most people prefer the uniformity of round or off-round pearls.

  Surface Texture

Raised areas and other imperfections can appear in the surface of a pearl if the layers of nacre do not adhere smoothly. The smoother the surface, the more highly sought-after a pearl is. Pearls with slight surface imperfections can offer the consumer a good value.

Surface texture can also help you tell a real pearl (natural or cultured) from a fake. When you run a real pearl over your teeth, the surface feels gritty, while the surface of a fake pearl feels smooth.


Pearl size is measured in millimeters (mm). The type of pearl affects its size. Freshwater pearls range in size from about 3.0 to 7.0mm and Akoya pearls range from about 6.0 to 8.5mm. South Sea and Tahitian pearls are the largest, reaching sizes up to 13mm.

  <Pearl Size- Katarina

Pearl nacre can be somewhat delicate. Wearing pearls often is good, as the body's natural oils keep pearls lustrous. But household chemicals including perfume and hairspray can dull the luster of your pearls. Remember this simple rule: last before you leave, first when you come home. That is, put your pearls on last when you get ready, and take them off first thing when you get home. Before putting your pearls away, wipe them with a soft cloth. (Never put them in an ultrasonic jewelry cleaner.) Always store pearls separate from other jewelry to avoid damage.

Types of Pearls
  Freshwater Pearl
  Akoya Pearl
  South Sea Pearl
  Tahitian Pearl
  Unusual Pearl
Freshwater Pearl
Round freshwater pearls look very similar to Akoya pearls, but are available for a much lower price. This is because these cultured pearls come from a type of mussel that yields several pearls at a time and that can be harvested many times. Compared to Akoya pearls, freshwater pearls are generally smaller and less symmetrical. At as little as one-fifth the price of Akoya pearls, freshwater pearls offer good quality at an excellent value.
Most freshwater pearls come from China. Unlike saltwater pearls like the Akoya, South Sea, and Tahitian, freshwater pearls are cultured by implanting a piece of tissue from a donor mussel instead of a bead. It takes from three to seven years to grow a freshwater pearl.
Fresh Water Pearl - Katarina
Colored Freshwater Pearls

Freshwater cultured pearls are available in a wide variety of colors. Many popular colors including pink, yellow, and other pastels can be achieved naturally, by controlling the pearl mollusks' diet and the amount and type of trace metals in the cultivating environment.
Treating freshwater pearls to achieve a particular color is a widely accepted practice. Freshwater pearls in a strand may be treated to even their colors and make them match better.
Pearls whose color is natural are more valuable than pearls that have been treated to change their color. When buying pearls, make sure it is clear whether or not the pearls have been treated—they should be less expensive than comparable pearls with natural color.
Shop Freshwater Pearls

Colored Fresh water Pearl- Katarina
Akoya Pearls
The Akoya cultured pearl is the classic pearl—smooth, symmetrical, and lustrous—and is commonly used in pearl strands and earrings.
Most Akoya pearls come from Japan, and were the first type of pearl to be cultured, starting in the early 1920s. It takes between 8 and 24 months to grow an Akoya pearl.
The Akoya looks similar to the freshwater pearl but is generally larger, smoother and rounder, and has a deeper luster. Because of these qualities, Akoya pearls are higher priced than freshwater pearls.
Naturally occurring colors include silver-white, cream, rose, gold and gray-blue.
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Akoya Pearl - Katarina
South Sea Pearls

The oysters that grow these pearls can reach up to 1 foot in diameter, and they produce the largest pearls in the world. South Sea pearls come in a wide variety of naturally achieved colors, from silver-white to dark gold, and a range of pastels.
South Sea pearls are grown in warm salt waters, primarily off Australia, Indonesia and the Philippines. It takes 20 to 24 months to grow a South Sea pearl, and the oysters that form the pearls are delicate. They can only be grown in areas where the water temperature is very stable, as swings in either direction are fatal to the oysters. The difficulty of cultivating these pearls makes them rare and expensive.
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South Sea Pearl - Katarina
Tahitian Pearls

Tahitian pearls are grown in the waters of French Polynesia. Only 1 in 10,000 oysters produces a pearl and because of this rarity, they cannot be mass produced. It takes 22 to 26 months to grow a Tahitian pearl.
Tahitian pearls are silver, black, deep purple or brown with a variety of overtones including rose, green and blue. Black Tahitian pearls with green overtones are called "peacock" because of their resemblance to that bird's iridescent feathers. The darker colors result from the black lip of the oyster shells in which the pearls grow.
Tahitian pearls are larger than freshwater or Akoya pearls, often rivaling South Sea pearls in size.
In recent years, the deeper shades of the Tahitian pearl have become very fashionable, and the Tahitian is growing in popularity.
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Tahitian Pearl - Katarina
Unusual Pearls

While freshwater, Akoya, South Sea and Tahitian pearls are the most common, you may see these other types of pearls in the marketplace.

  Eyris Pearl
A variety of mabe (pronunciation: MAH-bay) pearl—hemispherical pearls, flat on one side and convex on the other—Eyris pearls are cultured in a type of abalone in the waters off New Zealand. The abalone is one of the most difficult shellfish to cultivate, and production of Eyris pearls remains limited; their rarity makes them higher priced. They have a beautiful natural color, blue with overtones of green, gold or violet.
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Eyris Pearl
  Conch Pearl
This type of pearl cannot be cultivated, making it one of the rarest in the world. They come from the Queen Conch, found in the waters of the Caribbean. Technically the conch pearl is not a pearl, as it is composed of a different material than nacre. Most are red or pink in color.
Conch Pearl
  Scallop Pearl
One of the newest varieties in the marketplace, this natural pearl comes from scallops that live in the waters of the Pacific off Baja California. They bear mosaic-like patterns and can be white, tan, salmon or mauve in color.
Scallop Pearl - Katarina
  Quahog Pearl
Produced by the quahog clam in the waters of the Atlantic Ocean along the New England coast. While the quahog clam is common, only a tiny number of them produce pearls. But keep an eye out at your next clambake—people have discovered pearls while eating cherrystone or littleneck clams! The rarity and beautiful purple color of this type of pearl makes it very valuable. They are the only naturally purple-colored saltwater pearl of any significant size. Recently, an extremely large (15mm) quahog pearl found in Rhode Island was valued at up to $1 million.
Quahog Pearl - Katarina