Glossary of Pearls

Prior to graduating from GIA as a Gemologist, I invested significant time and effort in pearl lab and trainings at GIA, and love, as a GIA Graduate - Pearls,  having the chance to share this info. 

Should you have questions about pearls, please contact The Talisman Collection by phone or by using the contact form on this site.  We are always happy to help.


This glossary contains the following info:

1.    General Pearl Info

2.    Types of Pearls

3.    Valuation of Pearls

4.    Care for Pearls


1.  General Info About Pearls


Pearls come from mollusks.

 Mollusks live in two aquatic environments:

·      Fresh Water

·      Salt Water


Pearls come from mollusks such as mussels and oysters.  Pearls can grow inside of any bivalve mollusk.  A bivalve mollusk is one that has two shells that come together.  Pearls can also come from snails, called “Melo” pearls, as well as from conchs.  Conch pearls are very valuable are fairly rare.


Mollusks secrete a substance that layers an object inside the creature which makes pearls have color and iridescence.  The production by the mollusks of the layers of coating takes years.  This coating is called “nacre”.  The more layers of nacre, the better the lustre.


A pearl is either:

·      Natural (nature made it – man did not inject anything into the mollusk to culture the pearl).

·      Natural pearls are harder to find, take longer to grow, and in fine quality, draw significantly higher value than cultured pearls. 

·      Natural pearls are most commonly found in oysters.


·      Cultured (man induces growth of the pearl by injecting a foreign object such as a bead.)

·      To culture freshwater pearls,  the shells of the mussels are slightly opened, small slits are cut into the mantle tissue and a small piece of live tissue from another mussel is inserted into those slits. The shape of the nucleus and its position in the mussel determines the shape of the cultured pearl. The shapes recovered include rounds, pears, eggs, drops, buttons, dome, and baroques. Most cultured freshwater pearls are composed entirely of nacre which leads to their high luster and quality.

·      Cultured freshwater pearls are commonly found in mussels.

·      Cultured saltwater pearls are commonly found in oysters.

Pearls grow in mollusks in two aquatic environments:

·      Fresh Water

·      Salt Water


Fresh water pearls, found or cultivated in freshwater mollusks in lakes, rivers, creeks, or ponds, they are often irregular in shape, but also can also be perfectly round and come in a wide and stunning range of colors.


Salt water pearls are typically found or cultivated in salt-water oysters in a bay, ocean, gulf, or sea. These also can be irregular in shape, especially when natural, although the best cultured ones are known for their fine round shape.


2.  Types of Pearls


South Sea Pearls are primarily cultured in the waters of Australia, the Philippines and Indonesia. The distinction between South Sea Pearls and Tahitian or Black South Sea Pearls are the oyster in which they are cultivated. The South Sea Pearls are cultured in the silver or gold-lipped pearl oyster and the color of the South Sea Pearls is usually white or silver colored, but they can also come in shades of yellow (golden) or blue-gray with pink or green overtones.

The gold-lipped pearl oyster used to culture these pearls (Pinctada maxima) is the world's largest pearl mother and is considered by experts to produce the best pearls in the world. The sizes of the pearls produced range in size from 10 to 20 millimeters, though pearls larger than 16 millimeters are rare. Their rarity and exceptional sizes make them highly prized. These are some of the largest and most expensive pearls available.


Sometimes referred to as “Black South Sea Pearls”, “Tahitian Pearls" are cultured in areas stretching from the Cook Islands, eastward through Tahiti to the Tuamotu Archipelago and the Gambier Islands in French Polynesia. They are grown in the black-lipped pearl oyster (Pinctada margaritifera) found in the atolls of these areas. The colors produced vary widely from purple, green, black and shades from gray to cream and even white. The rarest and highly sought after color is "peacock" - the greenish black color of a peacock feather.  Talisman Collection buys these pearls primarily from Mastoloni Pearls.

Black Tahitian Pearls are generally the same size as White South Sea Pearls ranging in size from 8 to 21 millimeters.

Akoya Pearls are the most well known type of salt water pearl and are cultured from the Akoya oyster (Pinctada fucata martensii). Most Akoya Pearls are cultured in China and Japan.  Originally, they all came from Japan.  The Akoya pearl oyster measures only six to nine centimeters across - less than half the size of Australia's silver-lipped pearl oyster. Smaller nuclei are implanted so the resulting pearls range from 2 to 10 millimeters in diameter. Considered the classic amongst cultured pearls and known for their perfectly round shape and high luster, Akoya Pearls are produced in white and cream shades with silver or pink overtones. 

Freshwater Pearls are round, oval or sometimes irregularly shaped pearls that are grown in various species of freshwater mussel. Typically their size ranges from 2mm to 12mm and the colors range from pink, bronze, lavender, to white. Increasingly you will see black freshwater pearls, but black is not a natural color of the freshwater pearl. The pearls are dyed to achieve this coloring.  Look at the hole in the pearl to see the layers of nacre.  Often, it is possible for the naked eye to see the dye.

Natural freshwater pearls occur in mussels for the same reason that saltwater pearls occur in oysters. Foreign material, usually a sharp object or parasite, enters a mussel and cannot be expelled. To reduce irritation, the mollusk coats the intruder with the same secretion it uses for shell-building, nacre.

To culture freshwater pearls, the shape of the nucleus and its position in the mussel determines the shape of the cultured pearl. The shapes recovered include rounds, pears, eggs, drops, buttons, dome, and baroques. Most cultured freshwater pearls are composed entirely of nacre which leads to their high luster and quality.

Biwa Pearls are ultured freshwater pearls that are grown by a freshwater mussel located in Lake Biwa in Japan. The term "Biwa pearl" may be used to describe any freshwater pearl that comes from any freshwater mussel in Japan.

Button Pearls are round pearls that are flattened to some degree, making them resemble a button or perhaps a disk rather than a perfect sphere. Often they are flat on one side or both sides. They tend to be quite uniform in shape and size, and are popular as spacers in necklaces. 

Mabe Pearls are a type of cultured pearl that forms on the shell of a mollusk. When cut away from the shell it has an unfinished flat surface on the back that is polished. Mabẻ pearls are most commonly dome shaped like a cabochon.  They were first produced in 1896 by Kokichi Mikimoto by inserting an irritant in the mollusc and later removing the nucleus and replacing it with a half-sphere of mother-of-pearl.

Blister Pearls  are natural pearls caused by the chance intrusion of a parasite through the outer shell of an oyster. The mollusc secretes nacre over the irritant, cementing it to the shell itself. Blister pearls are frequently irregular in shape.


Baroque Pearl is a type of pearl that is not rounded and left irregular in shape.  Cultured freshwater pearls are most commonly baroque, because freshwater pearls are mantle-tissue nucleated instead of bead nucleated. Thus these pearls are rarely perfectly spherical and can appear oval.


Keishi Pearls are formed when the oyster rejects the implanted nucleus before the culturing process is complete, or form after the cultured pearls have been removed. These oysters eventually produce pearls without a nucleus that are 100% nacre. Keishi come in a wide variety of colors, and tend to be very lustrous. They are 'petal' or 'cornflake' shaped irregular pearls - the word keishi means poppy seed in Japanese, and these pearls are often also referred to as 'poppy seed' pearls.


Potato Pearls are roundish pearls with a slightly oblong shape and less-symmetrical curves, resembling more a potato than a sphere. Most potato pearls are freshwater cultured pearls from China. They are a very affordable substitute for round pearls, and are popular with jewelry-makers for that reason. Larger potato pearls with good surface and lustre still make gorgeous necklaces. There is a wide variance in quality among potato pearls, with the lowest quality characterized by rings or grooves and bad shape, and the highest quality being almost on par with near-round pearls.


Ring Pearls are usually potato pearls (see above) that have very pronounced growth rings. Previously seen as a sign of poorer quality, these pearls are becoming more and more sought after as these 'love rings' and blemishes give them a unique, organic quality that is admired by designers and becoming very fashionable.


Rice pearls are elongated freshwater pearls with a crinkled or ringed surface, many of which resemble a grain of rice. The more oval-shaped the pearl, the higher the value, especially if it does not have rings or other surface imperfections. The more wrinkled the surface, the lower the value, making these some of the most inexpensive pearls available on the market.


Round Pearls are pearls that are almost perfectly spherical, which is the shape most people consider when they think of a pearl. Because of their relative rarity and "classic" nature, they are highly desirable. But as the shape approaches closer to round, the price can rise exponentially. “Round” classification can include pearls that are “near-round” or “almost-round”, and it is sometimes difficult to know where to draw the line between “round” and “potato.”


Imitation Pearls are simulated pearls manufactured entirely by man or machine. They have no real value as a gemstone. They can be made from glass, ceramic, shell, or even plastic. The bead is then coated with varnish and/or other materials in order to produce a pearl-like lustre and iridescence.

A common test to determine whether a pearl is genuine or imitation consists of scraping the pearl gently across one's teeth. Imitation pearls feel smooth to the tooth, while genuine pearls feel slightly gritty or abrasive. Also, if the pearls are perfectly smooth, round and uniform, they are likely imitation pearls.  Be careful.

Mother of Pearl is the basic substance that is secreted by oysters and mollusks to form the inside of their shells. It is the same substance that also forms the layers that compose pearls.

Shell Pearls are man-made pearls, produced by coating a mother-of-pearl shell nucleus with many fine layers of powdered pearl dust, which are then baked and polished. These pearls are considerably better quality than other simulated pearls and often pass the 'abrasion test' used to identify natural and cultured pearls. When in doubt, always ask the seller for confirmation of authenticity in writing. 


3.  Judging the Value of Pearls

The Talisman Collection, when performing an appraisal or valuation of pearls, performs x-rays of pearls to see the layers within if the claim is that the pearl is “natural” so that we can see the layers of nacre and whether a bead was inserted.  There’s really no other way to do this.  For these x-rays, we work with equipment that is the same as what dentists use to x-ray teeth.


Here are some initial steps toward ensuring value when buying pearls:

First and foremost, buy from a reputable seller whom you trust.  Pearls are opaque, making it easy for the untrained eye to see beauty but not know what is on the inside.  Some pearls look spectacular but after being stored or worn, lose their lustre and/or color because of the treatments that were used to sell the pearl.  Summarily, with pearls, you get what you pay for.  Fine quality pearls are costly and last for generations.  Consider the following characteristics:



Low lustre pearls appear milky or chalky.

High lustre pearls reflect light well and show mirror-like reflections.

Put your pearls on a white surface or a white cloth near a window on a reasonably bright day and see how the pearls reflect the window frame. The clearer the reflection, the more lustrous the pearls.

As with natural pearls, high quality lustrous pearls make up only a fraction of the pearls available on the market, and command the very highest prices.

Since a very lustrous baroque pearl is probably more desirable than a round milky pearl, lustre is generally considered to be one of the most important aspects of a pearl’s grading and valuation.



Pearls come in a fascinating variety of shapes.  Although the rounder the pearl, the more valuable it is, baroque and off-round shapes are also very popular and can be of tremendous value.

Round is generally the most expensive variety. A proper round pearl is symmetrical and will roll in a straight line. Again, only a small percentage of total pearl production will give you true round pearls.  Look to see if the pearls in your strand match, shape-wise.

There are various terms such as ‘near round’, ‘off-round’, ‘almost round’, all used as indications that the pearls are ‘roundish’ in various degrees.

Other terms used are egg round/oval or potato which indicate an ‘extended’ round shape – but which can often look round. You might find that these pearls will look round in photographs and where the shape is not stated, you will quite often ‘perceive’ them to be round. These would usually be covered in the Semi-baroque category.

Semi-baroque is a general term that typically covers regular shapes of pearls that are neither round nor off-round and would include button, pear, rondelle, drop shapes and ovals as mentioned above.

Baroque is a general term that indicates an irregular shape. Whilst typically they are the most inexpensive type of pearls, certain specimens can be more valuable than round pearls. Famous baroque pearls have been designed as special jewelry pieces throughout history.



Pearls come in a wide range of natural colors/shades, and many pearls are dyed to suit fashion requirements. Natural colors include the whites, creams, pinks, lilacs, silver and gold shades as well as black for the Tahitian pearls from the black-lipped oyster.

Besides the body color, in more expensive pearls you will usually find color overtones which reflect the pearl’s heart; for example, a white pearl may have a silver or light pink overtone.



The fewer blemishes a pearl has, the more valuable it is. Blemishes are marks, bumps or little pot holes which, in reality, give each strand its unique identifying factors.

To find pearls without blemishes is rare and their price is likely to be astronomical, given other quality factors being high. One has to remember, pearls are organically grown and just like the human body, no two are exactly alike.

Think of blemishes on pearls as moles or fingerprints. However, any serious damage (e.g. cracks, nacre chipped off, etc.) to the nacre is to be avoided as almost certainly this will affect the longevity of the pearl.

When assessing pearls, always look at each pearl individually and carefully to judge the surface quality.



The larger the pearl, the more valuable it is. Usually it would have been in the mollusc longer, thus incurring a longer/higher investment cost.

Each of the main types of pearls has a common range of sizes:

    Freshwater pearls typically range from 3mm up to 12mm,

    South Sea or Tahitian Pearls start from around 8mm right up to 18mm or larger.

    Akoya pearls average 4mm to 10mm.

Identical pearls of the same quality in sizes up to 5.5 or 6mm do not vary greatly in price. It might be 10/20% more for the next 0.5 or 1mm up in size. However, a jump of 1mm after 6mm, especially around 8 or 9mm (considered large), will cause the price to jump 50% or even 100%



4.  Basic Care for Pearls

Don’t get chemicals on them.

Don’t wear them for sports or when heavily perspiring.

Don’t wear them in very intense sun.

Wrap them with a soft cloth when storing them, and don’t let them rub against each other or other necklaces.

Try not to drop them.

Do not get perfume or lotion on them.

Have them professionally cleaned and strung.  Do not attempt to do this at home.

Treat your pearls with great care.  They are fragile. 



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