FAQ - Introduction to Pearls

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Pearls can tend to all look the same to the casual observer. However, different pearls may vary widely in quality and rarity, giving rise to a vast range of market prices. Before investing in a string of pearls, you should first become acquainted with some basic knowledge about pearls.

What Is A Pearl?

A pearl is a natural gem created by a living organism such as an oyster. When an irritant or foreign object is introduced into an oyster or another mollusk, the animal coats it with a substance called nacre, the same material with which it builds its shell. Nacre is made up of tiny crystals of calcium carbonate, aligned in such a way that light is reflected and refracted to produce a rainbow of light and color. Over time, the layers of nacre build up to form a complete pearl.

1. What Are Cultured Pearls?

Today cultured pearls are grown using a similar process as natural pearls, except that the irritant is placed into the mollusk by a skilled technician. Freshwater cultured pearls are “nucleated†with tissues so that the quality of cultured pearls are as close as possible to natural pearls in growth. Saltwater Akoya, Tahitian, and South Sea cultured pearls are bead nucleated. This means that the nacre is formed on a round bead, resulting in rounder pearls. Round pearls are extremely rare in non-cultured pearls. Today, almost all pearls in the market are cultured.

Pearl Types

1. Freshwater

  1. Average size range: 6mm to 7mm
  2. Color: Whites and pastels
  3. Nucleation: Tissue
  4. Environment: Freshwater ponds
  5. Cultured in: Triangle shell mollusk (Hyriopsis Cumingi)
  6. Growth time: 2 to 6 years
    Notes: Since freshwater pearls are tissue nucleated, the rounder the pearl, the higher its value. Also, the pearls are considered 100% nacre.

2. Akoya

  1. Average size range: 6mm to 7mm
  2. Colors: White with subtle overtones
  3. Nucleation: Bead
  4. Environment: Saltwater protected bays, lagoons and other similar bodies
  5. Cultured in: Akoya oyster (Pinctada Fucata)
  6. Growth time: 8 months to 2 years
    Notes: There are two major regions for pearl growth – China and Japan. The Japanese created pearl culturing and had almost a century of experience. Chinese cultured pearls are newer to the market and tend to grow faster. Japanese Akoya commands a higher prestige and value while Chinese Akoya tends to be better bargain buys.

3. South Sea

  1. Average size range: 12mm to 13mm
  2. Colors: White and golden
  3. Nucleation: Bead
  4. Environment: Saltwater protected bays, lagoons and other similar bodies
  5. Growth time: 20 months to 2 years
  6. Cultured in: Silver and Gold Lipped oyster (Pinctada maxima)
    Notes: These are the largest of cultured pearls. Also, they are the most valued for their rarity. Concerning color, the more saturated the golden color, the higher the value.

4. Tahitian

  1. Average size range: 10mm to 11mm
  2. Colors: Metallic colors ranging from silver to dark black
  3. Nucleation: Bead
  4. Environment: Saltwater protected bays, lagoons and other similar bodies
  5. Cultured in: Black Lipped oyster (Pinctada margaritifera cumingi)
  6. Growth time: 22 to 28 months
    Notes: Tahitian pearls are mainly black and are the second largest cultured pearl. Some experts combine them with South Seas as they are grown in the same general part of the world. However, their appearance is very different, and they are grown within different species of mollusks.

2. Pearl Appearance and Value

Pearl Color

Cultured pearls come in a variety of natural colors from brilliant white, colorful pastels to dark blacks. Some pearls are also treated for color. Treating pearls is permanent and allows for color options that were not previously available. Treated black Akoya pearls have been available in fine jewelry houses since the 1930's.
The overtone of a pearl is the hue the pearl reflects in different light settings. Color and overtone can be affected by ambient light as well as the light source. Fluorescent light can bring out more greens and blues while incandescent bulbs will bring out more reds. Certain colors and overtones command higher values. However, the choice should be made based on the wearers' complexion and his or her preference. Here are a few preferred colors for different types:

  1. Freshwater: Brilliant white and pastels
  2. Akoya: White with pink, beige or silver overtones
  3. South Sea: Deeply saturated golden
  4. Tahitian: Dark with peacock green overtones.

Pearl Size

The adage is that the larger the pearl, the more valuable it is. This is true, a larger pearl with similar value factors will be more valuable than a smaller one. However, there are size ranges where value increases exponentially. For example, Akoya average 6mm to 7mm. As a result, pearls within or under that range are more readily available than those that are larger. Larger than average pearls are rarer as detailed below.
More Rare and Valuable Size Ranges

  1. Freshwater: 7mm to 8mm
  2. Akoya: 7mm to 8mm
  3. South Sea: 12mm to 13mm
  4. Tahitian: 10mm to 11mm

Extremely Rare and Valuable Size Ranges

  1. Freshwater: 10mm and larger
  2. Akoya: 9.5mm and larger
  3. South Sea: 15mm and larger
  4. Tahitian: 14mm and larger


Luster is one of the most important factors when evaluating a pearl. The shine or luster is how well a pearl reflects both light and images. An example is comparing luster to a mirror. An outstanding luster will have a mirror like shine and very sharp image reflection. Reflected images will have clean lines. A pearl with good or excellent luster will be of higher value.


The value of cultured pearls is also determined by their roundness. Roundness is typically just determined by visual inspection. Since freshwater cultured pearls are nucleated with tissue, they will tend to be less round. However, less than 20% to 50% of bead nucleated pearls, such as Akoya, Tahitian, and South Sea, will be truly round. Some pearls in the market are also valued for their unique shapes (such as tear-drop pearls or crudely shaped Baroque pearls).


The surface or body of the pearl should be relatively free of blemishes. As pearls are natural gems, minor surface blemishes tend to occur in most pearls. A pearl with good luster will appear to be less blemished.