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Pearls: A Collector's Guide

The pearl is undoubtedly one of the world's most recognizable and sought-after gems.  Objects of personal adornment and gems worthy of distinction, pearls have embodied desire, sophistication and wealth since their discovery thousands of years ago.


With the infinite size, shape and color options available, selecting and purchasing a pearl can often be a daunting task. In this pearl collector's guide, we'll delve into a bit of history, types and key characteristics of pearls that should be considered upon acquiring this exceptional gem.





White South Sea pearl necklace


Historical Perspective

Because of its long history, many experts believe that the pearl was perhaps the first gem used for personal adornment. The earliest written record of the pearl exists in the writings of a Chinese historian which date to 2006 B.C. Nearly every culture, including the ancient Romans, Greeks and Egyptians held the pearl in great reverence. Members of the elite and royal bloodlines throughout history utilized the pearl of all varieties to adorn their drapery and crowns. The Byzantines, in particular, adorned their wardrobes and head pieces with hanging seed pearls - an admiration that was heavily documented in both writings and paintings.


During his voyages to the New World, Christopher Columbus encountered native peoples ornamented with natural pearls - and even ventured to discover pearl sources himself in present-day Panama and Venezuela. Word of these new sources traveled back to Western Europe and connoisseurship skyrocketed.


The mid-19th century witnessed an even greater surge of popularity for the pearl. In France, the access to pearls opened up ownership beyond the aristocracy and into the middle classes. Neighboring Great Britain enjoyed lavish displays of pearls as their imperialist territories in the Middle East and India, were the world's main source for pearls.


Birth of a Pearl

Simply put, a pearl is formed when an irritant enters an oyster, mussel, or clam. As a defense mechanism against the foreign entity, the oyster produces a fluid to coat the irritant in several layers. Ultimately the oyster's layering creates what we know as “nacre,” or what we know as the iridescent outer coating of pearls. This process takes a very long time. In most cases, for the very finest and largest pearls, it will take up to three years for a pearl oyster to form a pearl.


Location, Location, Location

Like many other gemstones, pearls can be found in a variety of different geographical regions. Just like rubies are more highly prized if they are from Burma, there exist certain sources that produce the finest pearls.

South Sea

Undoubtedly the finest type of pearls, the South Sea variety are the most sought after due to their size and unprecedented luster. In almost every case, the largest accepted size for a South Sea will be a colossal 20mm. However, in very rare instances, there will exist a South Sea pearl that measures 21mm.



A white south sea pearl strand that includes a 21mm white south sea pearl


South Sea pearls also have the thickest nacre of all other varieties, which gives them a durable life and an exceedingly attractive and smooth appearance.


Location Found: Waters of the Philippines, Indonesia, Australia

Color: Gold, White (sometimes, with silver overtones)

Average Size: 8mm-20mm


As the only pearl variety that is naturally dark, Tahitian pearls are most recognizable for the black and grey hues. While they are called “Tahitian,” Tahiti itself does not actually produce pearls. Rather, this pearl variety is grown in the waters of a group of five island archipelagos known as French Polynesia.



An ideal Tahitian pearl culminates the center of this ring

An ideal Tahitian pearl culminates the center of this ring


Location Found: Waters of French Polynesia

Color: Black, Grey, White (not all are simply black) with colored overtones

Average Size: 8mm-15mm



A Tahitian silver pearl necklace

Touted as the most classic variety of pearls, the Akoya is most known for its elegant round shape. In fact, they have been cultured the longest of any other variety of pearl and they are known exhibit a smooth, even luster.




Pearl and diamond earrings

Location Found: Waters of Japan

Color: White of grey (with pink or silver overtones).

Size: 6-12mm


Though not limited to a specific location, these are usually cultured in freshwater lakes and ponds in various countries around the world. Less expensive than pearls originating from the locations listed above,  freshwater pearls are produced in a wide range of sizes, shapes, and colors, and are smaller in size as compared to South Sea, Tahitian or Akoya.


Location: Freshwater lakes and ponds. China and the United States are the leading sources.

Color: numerous

Size: 3 - 10mm



Contrary to what many may believe, pearls are available in a wide array of colors and hues. While the vast majority are white, pearls are naturally grown in gold, grey, silver, and cream.


Importantly, many of these colors can possess and display certain overtones, which is the natural existence of a second hue that compliments the main body color of the pearl. In the trade, those with a green or purple overtone are touted as “aubergine” and those grey with pink or purple overtones are colloquially referenced as “peacock.”



A South Sea pearl necklace comprised of twenty-nine multi-colored pearls.

In many cases, pearls can and are “bleached” to achieve a more unique color. However, it is those colored pearls that naturally possess different hues that are the most sought after, command a much higher premium, and are exceedingly more rare.



Many experts agree that luster is one of, if not the most important, quality factor when considering a pearl acquisition. Luster is inherent to a pearl's attractiveness and outward beauty as it contributes directly to the “shine” of the pearl.





A white South Sear pearl necklace, comprised of twenty-three sumptuous white pearls displaying incredible luster.

A pearl that has high luster is that which has sharp reflections when it catches light reflections. As pearls vary by origin, there is a different standard for exceptional luster for each pearl variety.



Though closely related to the quality of pear luster, nacre specifically refers to surface quality and thickness of the gem. A pearl with good nacre is that whose surface is thick - thick enough to hide the nucleus, or interior, of the pearl. As you may assume, the quality and thickness of a pearl's nacre is directly associated with its inherent durability. A pearl with thin nacre will be much less durable, and therefore safely wearable, than that with thick nacre.



A limitless variety of shapes can be found in all varieties of pearls. Here are some of the most common:


Round pearls are perfectly spherical -- the shape most people think of when they think of a gem-quality pearl. This is the most desirable shape for a cultured pearl and the most expensive.

Near Round

Also known as "off round", pearls have a slightly oval or flattened shape. They can still have excellent qualities in terms of lustre or lack of blemish. Many freshwater pearls fall into this category.


Just as the name suggests, button-shaped pearls are flat in appearance and are often symmetrical. This shape is due to the pearl developing along the wall of the mollusk's shell, giving the gem a slightly flatter shape on one side and a slightly rounder form on the other.


This is a pearl which is both non-symmetrical and irregular in shape. The baroque pearl's "irregularity" can range from slight to completely abstract in its shape. Though round shapes tend to be rarer, Baroque pearls can be extremely unique thus increasing their desirability more than might be expected based on their shape alone.





A white Baroque pearl necklace, where the pearls measure 19.5mm to 18mm


The general rule of thumb for pearls is the larger the pearl, the more valuable. Pearls are measured in millimeters and typically vary from 2mm to 20mm.


Like the quality of pearl luster, it's important to note that there are different size “norms” for different varieties and colors of pearls. For Tahitian pearls, for example, a pearl will be noted as an exceptional size worthy of distinction if it is approximately 10mm or above. In most instances, a golden 10 mm pearl will be much rarer than a white pearl of a similar size and luster.


Quality Control

Like many other jewelry pieces, it's imperative to maintain good quality of your pearls, specifically a strand of pearls. Over time, the string that holds a strand of pearls together will weaken due to time and wear. As this is a common procedure, any local jeweler or gemstone specialist can assist in helping to restring your pearls with a fresh, sturdy strand.



Surface Quality

Pearls are not protected from natural incidences and therefore can, from time to time, display surface characteristics such as scratches and abrasions. If these characteristics are numerous, deep, very apparent to the unaided eye, or severe than they can be determinant to the value and durability of the pearl.


 In some cases, severe surface characteristics can be fixed by drilling holes or mounting to hide their appearance.


In most cases, perfumes and cosmetics can affect the surface quality and can potentially dull the appearance of pearls. Therefore, it is always best practice to keep these common cosmetic products away from your pearls - strand, earrings, and even rings.


Do They Match?

When purchasing a pair of earrings or a necklace, you'll soon realize that finding even two pearls that match in color, size, and quality is almost impossible.  Because every pearl is a unique masterpiece of nature, it is exceedingly difficult task to undertake. Especially with earrings, it is preferable to find pearls that match as closely to each other as possible. In the case of necklaces, it becomes even more complex. But if you do find that perfect pair of earrings or necklace that possess perfectly matched pearls, you've come upon a true jewelry masterpiece.





South Sea pearl drop earrings comprised of two ideally-matched pearls.

As with most things, with a little homework and a trusted source, making a decision on the ideal pearl to purchase becomes a lot less challenging. If you're in the market for an elegant pearl jewelry creation for you or a loved one, M.S. Rau Antiques is the perfect place to find it.


Explore all of the rare and important antique pearls currently in our inventory.





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