A pearl is a hard, shining object formed within the soft tissue of a living shelled mollusk such as an oyster or another animal, such as a mussel. Just like the shell of a mollusk, a pearl is composed of calcium carbonate in minute crystalline form, which has been deposited in concentric layers.
Both freshwater and saltwater mollusks produce pearls as a natural defense against an irritant, such as a parasite, bone, or even a grain of sand, entering their shell or causing harm to their sensitive bodies. The invasion of this irritant causes the oyster or mussel to slowly secrete layers of aragonite and conchiolin, which make up its shell. This results in the formation of a substance known as nacre, commonly referred to as “mother-of-pearl,” which encases the irritant and shields the mollusk from it.
To encourage the formation of mother-of-pearl, an irritant is manually placed into a mollusc (usually an oyster) during the commercial growth of pearls.
Nearly any irritation that enters the shell can naturally cause nacre to develop, producing some extremely rare and valuable pearls.
Although they are not composed of nacre, pearls may also be produced by other bivalve mollusks and gastropods.
In this article, we will focus on three broad classifications of pearls based on their sources. So without further ado, let’s thoroughly examine the various classes of pearls based on their properties, size, and price range.
Cultured pearls are pearls produced through a human-induced process. The process of pearl formation is quite slow. Thus, through a process called “pearl cultivation,” pearl farmers surgically insert an irritant into a shell bead nucleus inside the soft tissue of the oyster. From there, the layers of nacre are formed naturally in response to the irritant, just like with natural pearls. However, the nacre layer is smaller in cultured pearls than in natural pearls. This difference can be easily detected with an X-ray machine.
Cultured pearls are generally classified into five groups depending on their origin. These include akoya, tahitian, freshwater, white, golden South Seas, and Sea of Cortez pearls. These pearls are unique based on the parts of the world in which they are cultivated and the type of mollusk used in their cultivation. However, there are a few general properties of cultured pearls. Some of these properties are listed below:
Cultured pearls are slightly rough in texture.
Unlike most gemstones and precious metals, pearl luster is more than just a reflection on the surface. Luster, which is often described by synonyms like sheen, glitter, sparkle, or brightness, appears to come from within the pearl. The greater the intensity, the higher the brilliance. A pearl’s luster is said to be pearly iridescent.
Pearls have a Mohs hardness value ranging from 2.5 to 4, indicating that they are fragile and easily scratched or damaged if not properly cared for.
5. Chemical composition
All pearls have essentially the same chemical composition. This includes calcium carbonate (CaCO3), organic substances, and water.
6. Refractive index
The refractive index, also known as the index of refraction, is a measurement of the bending or refraction of a light ray as it passes from one medium to another. The refractive index of pearls ranges from 1.52 to 1.69.
7. Specific gravity
The specific gravity or relative density of pearls ranges from 2.65 to 2.78. This is a result of the variable composition of the pearls.
8. Color and appearance
The color and appearance of pearls vary based on the species of mollusk from which they are obtained. Pearls can be white, pink, silver, cream, gold, green, blue, ivory, black, pale yellow, gray, or brown in color.
Based on the amount of light they permit to pass through them, pearls vary progressively from translucent to opaque.
9. Common sizes and shapes
The sizes and shapes of cultured pearls are linked to their types. Thus, we will be examining them based on their types.
One of the tiniest varieties of cultured pearls, Akoya pearls, range in size from as little as 1.0mm seed-like pearls up to 9.0mm, and very rarely, growing up to 10.0mm. The most common and popular sizes range from 6.0 mm to 6.5 mm to 9.0 mm to 9.5 mm.
because of their smaller sizes, Akoya pearls are not as varied in size as other types of pearls. There are four basic types of Akoya pearl shapes:
- Round: A round pearl, as the name suggests, is one that is perfectly spherical in shape. It is the most preferred type of pearl shape; thus, it is more expensive than its counterparts.
- Near-round: A near-round pearl is close to round but not quite round in shape. It is the next most preferred pearl shape.
- Drop or pear-shaped: These types of pearls have a shape resembling a tear or a drop of water. They look like ovals, but one end is markedly narrower than the other.
- Baroque: Baroque-shaped pearls are pearls having an uneven, non-spherical shape. This is due to protrusions on either or both ends of the pearl. Circle baroques also include protrusions, but they are less apparent than regular baroques.
- Size: Tahitian pearls are significantly larger than Akoya pearls. They range in size from medium to enormous pearls. Tahitian pearls range in size from 8 to 18mm. However, the most prevalent sizes on the market range from 9 to 15mm.
- Shape: due to their larger size, Tahitian pearls offer a wild variety of options for you to choose from. These shapes are outlined in the chart below:
Round, semi-round, pear and baroque-shaped pearls have all been examined previously. Let’s take a quick look at the other shapes.
- Button: Instead of being a perfect sphere, button pearls are somewhat flattened, giving them the appearance of a button or even a disk. As the flattened side can be affixed to the setting, these pearls are frequently used in earrings. Since they have at least one axis of symmetry, they can be classified as symmetrical pearls.
- Oval: oval pears are sometimes known as rice pearls. They can be formed when two pearls in the same mollusc merge. Oval-shaped pearls, unlike pear pearls, are narrower at both ends than they are at the center. They are quite beautiful in appearance and serve varied functions.
- Ringed/circled: These are pearls characterized by concentric rings, ridges, or grooves encircling them. They are named along with the primary shape of the jewel, e.g, ringed round, circled oval, circled baroque, etc.
- Size: Freshwater pearls come in a wide range of sizes. They can grow up to 20 mm in size, making them the world’s largest cultured pearls alongside South Sea pearls. They are, nevertheless, the cheapest and most common type. Typical sizes found in the market include 7mm to 12mm pearls.
Due to the manufacturing process, freshwater pearls are rarely precisely spherical. They are generally irregular (baroque-shaped). Common shapes include a coin shape, button shape, stick shape, drop shape, off-round (near-round) shape, and very rarely, a circular shape.
South Sea Pearls
- Size: Along with freshwater pearls, south sea pearls are the largest type of cultured pearls in the market today. However, on average, they are usually larger than freshwater pearls, ranging in size from 8.0 mm to 20.0 mm, with an average size falling between 12.0 and 15.0 mm. Sizes larger than 15.0 mm are very rare and expensive.
- Shape: South Sea pearls come in a variety of shapes. The rarest of them being the rounded one. It takes about three years for this pearl to form, and during this long period, a number of factors may affect its formation, thus changing its shape. With that said, here is a list of the various shapes in which South Sea pearls come: round, semi-round, baroque, button, oval, and ringed.
Sea of Cortez pearls
- Size: The Sea of Cortez pearl usually measures about 8.9 mm, although it can be as large as 14.3 mm. Common market size ranges from 8.3 to 9.8 mm.
- Shape: Cortez pearls are available in round, semi-round, and drop shapes.
The Price of Pearls
Certain factors influence the price of pearls. These factors include nacre, luster, size, shape, color, texture, and rarity. The two most important factors are size and shape; the larger a pearl is, the more expensive it is. When it comes to shape, due to their rarity, perfectly rounded pearls are usually more expensive.
Having said all that, the prices of pearls follow this pattern:
Freshwater pearls < Akoya pearls < Tahitian pearls < South Sea pearls < (< means “less than”)
- Freshwater pearls: the price of high quality freshwater pearls ranges from $75 to about $5,000, depending on the aforementioned factors.
- Akoya pearls: the price of high quality Akoya pearls ranges from $500 to about $10,000.
- Tahitian pearls: the price of high quality Tahitian pearls ranges between $2000 to $25,000.
- South sea pearls: the price of high quality south sea pearls ranges from $3,000 to $ 100,000.
- Sea of Cortez pearls: cortez pearls are very rare, with just about 4,000 of them produced annually. Top quality Cortez pearls range between $3,000 to $100,000
Note that these prices are not fixed and may fluctuate depending on dealers and other criteria not given here. However, this is a fairly realistic representation of what you should anticipate when shopping for the finest in each category.
Natural pearls, unlike cultured ones, do not start with a human-induced process. Natural pearls are formed when an irritant lodges itself inside a pearl-producing mollusk such as an oyster, sea snail, abalone, or mussel.
The mollusk’s defense mechanism reacts by trapping this irritant in a sac or nucleus and continuing to deposit layers of shiny, protective layers of a substance called nacre on this nucleus over several years. This is the process by which natural pearls are made.
Based on their sources, natural pearls can be classified into two groups: saltwater pearls and freshwater pearls.
1. Natural Saltwater Pearls
Natural saltwater pearls, as the name suggests, are naturally occurring pearls that develop in saltwater mollusks. These types of pearls are nearly impossible to find nowadays because of a number of factors, some of which include bans on open-water pearl diving, ocean pollution, natural predators, and the inherent danger involved in pearl diving.
These factors have played key roles in discouraging people from diving for pearls.
Furthermore, according to statistics, just one in every 10,000 oysters produces pearls suitable for use. These odds are hardly enticing and not worth the risk of pearl diving. Thus, this practice has almost completely ceased, and if you are lucky enough to ever come across a natural saltwater pearl, you can be certain that it is an antique and that the owner has undoubtedly spent a significant amount of money in acquiring it.
Natural saltwater pearls have mostly similar physical characteristics to their cultured counterparts. However, a singular characteristic sets them apart: nacre concentration.
Because no human insertion is made to speed up the process, mollusks continue to secrete layer upon layer of nacre for several years to form a pearl. When these pearls are held up to a powerful light source, concentric growth lines indicating where layer after layer of nacre was added can often be seen.
Natural saltwater pearls also have more luster than natural freshwater pearls.
- Common sizes and shapes
Natural saltwater pearls can occur in almost any size because they develop relatively uncontrolled by human activities.For instance, the Giga pearl, the largest natural pearl in the world, was able to reach dimensions of 39.37 cm (15.5 in) by 22.86 cm (9 in) by 20.95 cm (8.25 in) before being harvested.
Natural saltwater pearls come in various baroque shapes; very rarely will you find a perfectly rounded natural pearl.
Due to their rarity, the cost of natural saltwater pearls is usually astronomical, ranging from several hundreds of thousands to millions of dollars depending on their size and quality.
2. Natural Freshwater Pearls
Natural freshwater pearls form through the same process that gives rise to saltwater pearls; however, they form in a different type of mollusk (a mussel). Since they are found in more easily accessible freshwater and produced in larger quantities, natural freshwater pearls are more common than their saltwater counterparts.
The chief difference between freshwater pearls and saltwater pearls is the difference in luster and quality. Whether cultured or natural, freshwater pearls typically have a lower luster than saltwater pearls.
- Common sizes and shapes
Freshwater pearls are typically smaller in size than saltwater pearls and come in a wider variety of shapes. Perfectly round pearls are also very difficult to come by in this category.
Natural freshwater pearls are cheaper than natural saltwater pearls but more expensive than cultured pearls.
How do I decide which to choose?
Choosing the right kind of pearl to spend your hard-earned money on can be a bit tacky sometimes. Not to worry though; we’ve got some great tips to help you decide which is just right for you.
A piece of jewelry should never put you in a bad financial position. And I can promise you that pearls can make that happen. Freshwater pearls are often the least expensive type of pearl to buy.
However, if you have additional funds, you can slowly go up the scale of taste and elegance, taking the time to consider all your options along the way.
Another fundamental rule is that cultivated pearls are typically less expensive than natural pearls, so be sure to look into the many types of cultured pearls on the market.
Pearls are believed to complement any skin tone, hair color, and eye color. They have a sleek, minimalist appearance and blend well, bringing elegance to your chosen clothing. Just remember that you can’t go wrong with any pearl design.
Pearls, the only gemstones of organic origin, have been highly valued for generations. They are incredibly timeless and never cease to impress viewers. Pearls are stunning just as they are, unlike other gemstones that need to be mined, cut, and polished. This is a result of a number of factors typical to them, chiefly pearly iridescence (the luster in pearls that appears to come from within the pearl).
Whether you opt for a cultured or natural pearl, rest assured that you are making a choice with a lot of charm and versatility.