A Complete Guide to Freshwater Pearls: Characteristics & Much More

So, saltwater pearls may appear to be stealing most of the glory in terms of quality and desirability as a whole, but there is a lot to be said for the freshwater pearl.

While they may not quite compare in terms of overall quality, the freshwater pearl has certainly been on a journey. And on that journey, the cultivation techniques have greatly improved and yielded some fantastic results!👏🏻

Today, we are going to dive into everything you need to know about freshwater pearls so you can decide for yourself whether or not they are the type of pearl for you!

A Complete Guide to Cultured Freshwater Pearls

Basics: What is a freshwater pearl?

The freshwater pearl can be found inside of a freshwater dwelling mussel. Large freshwater ponds and lakes are home to the mussels that grow the freshwater pearl in a similar way that the oyster develops its saltwater cousin.

For the freshwater pearl, the mussel is inserted with a foreign material that the mussel cannot expel.

In irritation, and to protect itself from the agitation of the foreign object, the mussel coats the foreign object with a silky nacre which in time forms into a satiny freshwater pearl. The farmers slightly open the mussel and make small slits inside both mantle tissues before placing the foreign body inside.

The foreign substance is sometimes the mantle tissue itself or it could be a bead nucleus (but more on that in a hot tick!)

The history of freshwater pearls

While China gets a lot of attention surrounding freshwater pearls, the original cultivation of these luscious globes began in Japan following the cultivation of the saltwater pearl.

After the initial success of saltwater pearl production, the Japanese farmers began experimenting with freshwater mussels in Lake Biwa, a wondrous lake near Kyoto.📌

The 1930s is where freshwater pearl crops started appearing and they have only expanded and grown in popularity since then. Up until recently, all freshwater pearls were considered "Biwas" in reference to their heritage but, when pollution endangered the pearl farms and production slowly diminished…It was China who filled the gap in the market.

The Chinese Pearl Waves
Between the 1970s and 1980s was considered the First Chinese Pearl Wave followed by the Second Wave between 1984 and 1991. Both were considered trivial and unimpressive with pearls that were oddly shaped, lacked luster and produced undesirable colors. But this was a learning curb for the Chinese farmers who were quick to experiment and improve pearl production…and that they certainly did!

The Third Chinese Pearl Wave came along in the 1990s and China upturned the market with a pearl revolution! Pearls that matched the quality and luster of the original Biwa pearls (and sometimes even surpassed it).

The cultivation techniques of freshwater pearls: Tissue-nucleated vs. Bead-nucleated

Alright, now we’re going to start getting into the nitty-gritty of it. There is more to meet the eye to the often considered less-superior freshwater pearl that may surprise you.

There are two different cultivation techniques when it comes to pearl cultivation techniques: tissue-nucleated and bead-nucleated.👨🏻‍🏫 Don’t freak out! If you’re wondering, "What are you talking about?!" We’re going to break it down for you right now…

As we know, for the mussel to produce a pearl it must be inserted with a foreign substance in which to wrap its glossy nacre. And it is this part of the cultivation process which distinguishes which is a tissue-nucleated pearl and which is a bead-nucleated pearl.

Tissue-nucleated (non-nucleated) freshwater pearls

Unlike the saltwater pearl, traditional cultured freshwater pearls use the tissue-nucleated (also known as non-nucleated) technique to produce the pearls inside the mussel.

What does this mean?

The foreign object placed inside the mussel is actually a piece of donated mantle tissue which in this technique, is what is regarded as the "nucleus".

This contributes to a number of varying factors when it comes to these particular types of freshwater pearls:

  1. Tissue-nucleated pearls do not have a bead nucleus in which to guide the shape and growth of the pearl. Because of this, they are often almost all nacre and very rarely pop out a wonderfully round pearl. Instead, the harvest mostly produces baroque and semi-baroque shapes alongside button, drop, circled and keshi.
  2. A pearl composed entirely of solid nacre such as the non-nucleated pearl, is more durable and can better withstand the test of time.
  3. Up to 24 to 32 (sometimes up to 50!) tiny pieces of mantle tissue can be inserted into any one mussel which means each harvest, these non-nucleated freshwater mussels can produce a far greater volume of pearls than any saltwater oyster can.

Bead-nucleated (nucleated) pearls

The non-nucleated technique is the term used for a tissue-nucleated mussel. And these do account for most freshwater pearls which explain the varying shapes produced from the freshwater mussel.

A bead-nucleated (or nucleated) pearl contains a mother of pearl bead which acts as the irritant within the mussel or oyster. This cultivation technique is mostly used for saltwater pearl production however, a revolution in freshwater pearls cultivation means that certain types of freshwater pearl can be found with the bead nucleus (we discuss this further a little later on!)

They produce pearls that are closer to the perfectly round shape we often imagine a pearl to be and can also be bigger in size.

Where are freshwater pearls cultured?

We’ve touched upon a few areas already in which the freshwater pearl is typically cultured but let’s look into this in a little more detail.

Lake Biwa, Japan

Lake Biwa, Japan is truly where this all began. Although this is sometimes forgotten now that China is at the forefront of freshwater pearl production.

But the ORIGINAL cultured freshwater pearl followed in the footsteps of the saltwater pearl, which originated in Japan.🎌 Lake Biwa was the first freshwater lake where pearl farmers experimented with the creation of pearls formed within a mussel.

A large and outstanding lake near Kyoto in Japan, Lake Biwa was where the all-nacre Biwa pearls were cultivated, offering colors and luster not commonly seen in the saltwater pearl.

Up until recently, all freshwater pearls were considered Biwas however, now a pearl is only allowed to be referenced in this way if it is actually from Lake Biwa.

Lake Biwa pearl production thrived until pollution threatened the crops in the mid-1980s. Now, very few pearls are farmed in this region.


Today, China takes the lead for freshwater pearl production. When the Lake Biwa pearl production began to diminish, China was there to fill the gap!🏃🏻‍♀️

The Hyriopsis Cumingii (triangle shell) is the main source of freshwater pearls cultivated in China. Arguably, it wasn’t until the mid-1990s that Chinese pearl farmers actually mastered the technique of producing high-quality pearls.

Up until this point, China had experimented and tested with less than adequate results.

Their pearls were sometimes compared to "Rice Krispies" due to their low quality, odd shapes, and lack-luster appearance.

Steven KwokIGI Certified Pearl Grader
Now, China is at the forefront of freshwater production and has revolutionized the freshwater pearl industry by adopting the saltwater pearl cultivation technique of using a bead or shell nuclei as the mussel irritant.

These can produce bigger and rounder freshwater pearls that are incredibly desirable and sought after!

Second generation pearls
It was during the 90s that Chinese pearl farming really mixed things up and turned the industry on its head. It began returning healthy mussels back to water following their first harvest.

These mussels would continue secreting nacre within the pearl sack and form what are known as "souffle" or "keshi" pearls of unusual shapes and sizes. Quite exquisite and wonderfully unique!

United States

The United States also plays its part but cannot compare to the sheer volume and production of pearls produced in China.

The Mississippi River Basin is an established area for freshwater pearl production with the first experimental freshwater pearl cultivation founded in Tennessee in 1963.

Unsurprisingly, the scale of freshwater pearl farming is very limited in comparison to China!

White and Pink Freshwater Pearls

Two famous freshwater pearl varieties

We NEED to talk about the two famous and revolutionary freshwater pearl varieties that have given the freshwater pearl an entirely new representation in terms of quality and outstanding beauty.🥳

The Freshwater AK pearl and the Edison pearl have adopted the same cultivation technique as the saltwater pearl, using a bead nuclei (rather than a tissue nuclei).

And the results have been incredible!!

Let’s find out more about these two famous branded freshwater pearls…

Freshwater AK Pearls

  • The freshwater AK pearl is also known as the "film seed pearl" and is the very latest in bead-nucleated cultured pearl research.
  • The freshwater AK pearl is distinguishable by its smooth and even roundedness which is difficult to find in a tissue-nucleated freshwater pearl.
  • Oftentime they are anywhere between 5-9mm in size and the luster is considerably better than your typical freshwater pearl.
  • With over 2mm nacre, it oftentimes has a superior surface finish and is slightly more durable due to its bead nucleus.

Freshwater AK pearls vs. Saltwater Akoya pearls

While there is usually quite the difference in quality between the freshwater pearl and the saltwater pearl, freshwater AK pearls certainly rival that of the Akoya saltwater pearl.

They appear very similar in size and shape and the developed sophistication of the freshwater AK pearls even rivals the Akoya in luster and the smooth surface, and is considered superior to the Akoya!

Edison Pearls

  • Edison pearls may be considered the hottest new thing to market!📈 As the latest of Chinese pearl farm experiments, Edison pearls have only been on the market for several years.
  • Edison pearls, like saltwater pearls, are also inserted with a bead nuclei in order to reproduce the perfectly round and large pearls, and Edison pearls certainly are both of these things!!
  • The average size of an Edison pearl can range between a whopping 11-16mm. This is because, like the South Sea saltwater oysters, the freshwater mussel is generally nucleated one bead at a time (unlike other tissue-nucleated freshwater mussels that can be nucleated with up to 50 pieces of mantle tissue)
  • They are making a name for themselves for the intense, metallic-like luster and flashes of violet, magenta and blue overtones.
  • Their mostly smooth and luxurious finish sets them apart from their predecessors which often expressed a bumpy service which named them the "Ripple" pearl.

Treatments for freshwater pearls

Even the most extravagant of gems can be subject to treatment (take the diamond for example!) And freshwater pearls are not any different.

While a good quality freshwater pearl does not require any sort of treatment and is available at an affordable price, some are subject to a range of quality enhancements to improve color, surface quality, or luster quality.

The three common treatments that freshwater pearls may undergo include:

  1. Dying - Organic dyes are used to alter and enhance the color of the pearl, improving the color and adding a hint of a specific hue such as pink, metallic or blue.
  2. Irradiation - Gamma rays are used to darken the nacre layers in freshwater pearls.
  3. Luster treatments - Heat treatments, in some cases known as "maeshori", are used to enhance the luster of the pearl. In this process the pearl is heated and then cooled to offer a luscious glow.

Lower quality freshwater pearls often require treatment of some sort to enhance the overall quality and appeal, but with the rise in higher quality freshwater pearls…There are many that require no such treatment.

Freshwater Pearl Necklace

Rounding up: What are the characteristics of freshwater pearls? (vs. Saltwater pearls)

Let’s look at the different characteristics of freshwater pearls in comparison to saltwater pearls:

CharacteristicsFreshwater PearlsSaltwater Pearls
SizesFreshwater pearls can be found in a vast range of sizes. They typically begin at around 2-3mm and can reach between 9-10mm in size. However, the recent bead-nucleated freshwater pearls can grow even bigger than this and reach sizes of up to 16mm!The famous saltwater pearl variety Akoya ranges from 2-8mm in size. While most other saltwater pearls are larger than Akoya pearls and can reach up to 16mm.
ShapesThey come in all different types of glorious shapes! Often the bead-nucleated freshwater pearls create the closest to the round shape with most of the tissue-nucleated (non-nucleated) freshwater pearls including drops, baroque, semi-baroque, buttons, off-round, and more abstract shapes also.We see more perfectly round saltwater pearls than the freshwater counterparts due to the bead nucleus although saltwater pearls are also formed in a variety of shapes.
ColorsThey are found in body colors of white, yellow, orange, lavender, violet, and pink with varying overtones including blue, green, etc.Saltwater pearls come in white, yellow, gray, brown, black body colors and also have a range of overtones, such as pink, blue and violet.
Surface QualityAll pearls tend to have some sort of surface blemish. Freshwater pearl blemishes are usually seen as white chalk-like spots, tiny pinpricks, or small streak-like marks across the surface. Nucleated freshwater pearls tend to have a smoother finish than their tissue-nucleated counterparts.Saltwater pearls also have similar blemishes to freshwater pearls. Wrinkles are a typical characteristic on the surface of Akoya pearls, whilst threads are a common blemish that appears on Tahitian and South Sea pearls.
Nacre QualityFreshwater pearls have a thicker nacre than saltwater pearls with tissue-nucleated freshwater pearls being solid nacre.The Akoya pearl variety has the thinnest nacre. Other varieties generally have a nacre thickness of at least 0.8mm
Luster QualityFreshwater pearls generally display a soft and satiny luster. A diffused glow that offers a subtle and luxurious luster.The Akoya pearl has the brightest and sharpest reflection in the saltwater pearl category. The South Sea pearl is famous for their silky luster, while the Tahitian pearl has a chic and metallic look.

Grading the quality of freshwater pearls

The quality of freshwater pearls is usually determined by the 7 quality factors (6 of which were mentioned above!):

  1. Size
  2. Color
  3. Surface quality
  4. Shape
  5. Luster
  6. Nacre
  7. Matching

While there is no standardized grading system for pearls in the same way there is for say, diamonds, the A-AAA grading system is one that is widely adopted by jewelers.📝

In this grading system, AAA represents the highest quality pearl A represents the lowest quality of pearl (typically for commercial use). Four to five of the seven quality factors above are used in tandem with the A-AAA grading scale to determine the quality of a freshwater pearl and those factors are; surface quality, luster, shape, matching, and sometimes include nacre thickness.

Let’s break down each layer of the A-AAA grading system:

AAA Quality

  • Shape: Near perfect round.
  • Surface Quality: 95% clean to the naked eye but with less than 5% showing shallow inclusions. 1-2 deep inclusions are allowed.
  • Luster: Very high with bright reflections.👍🏻
  • Matching: Excellent match for size, body shape, color, tone, surface quality and luster.

AA+ Quality

  • Shape: Considered off-round or very slight off-round.
  • Surface Quality: 90% clean to the naked eye but with less than 10% showing shallow inclusions. 2-3 deep inclusions are allowed.
  • Luster: High to very high with good reflections.
  • Matching: Good match for size, body shape, color, tone, surface quality and luster

AA Quality

  • Shape: Off-round in shape including oval shapes.
  • Surface Quality: 80% clean to the naked eye but with less than 20% showing shallow inclusions. Multiple deeper inclusions allowed.
  • Luster: Dull to good luster with visibly blurry reflections that are not overly sharp or bright.
  • Matching: Fair match for size, body shape, color, tone, surface quality and luster.

A Quality

  • Shape: Off-round in shape including oval shapes.
  • Surface Quality: 60-70% clean to the naked eye. Clear and easily distinguishable blemishes throughout.
  • Luster: Dull and undefined reflections.
  • Matching: Fair match for size, body shape, color, tone, surface quality and luster.

How much is a freshwater pearl worth?

In comparison to the glamor and quality of the saltwater pearl, the freshwater counterpart can be anywhere up to 20%-50% cheaper.

The fast growth rates and often non-nucleated cultivation technique generally produce a comparatively lower quality of pearl with less uniformity and lower quality luster.

While the likes of the freshwater AK pearl and the Edison pearl are certainly beginning to rival the quality of saltwater pearls, they still don’t quite match up with the overall beauty and quality of saltwater gems.

As always the rarity of any given gem adds to its value and with saltwater oysters only able to produce up to 2-3 pearls per harvest, freshwater pearls are often in higher demand.

Today, some freshwater pearls can be found in wonderfully high quality, exhibiting a sumptuous silky glow and a wonderful delicate color yet, for the most part, they make for an affordable alternative to the higher-priced saltwater pearls.

Everything you need to know about freshwater pearls

And that’s it! You are now fuelled with all of the knowledge you need for your next pearl buying decision.🙌🏻

As an affordable option that in modern times can now be found in much higher quality than the history of freshwater pearls are used to, they make for a very popular pearl of choice.

Just be careful! Pearls are a soft and delicate gem no matter which variety you opt for. With that said, be sure to follow our top tips for caring for a freshwater pearl:

  • Put your pearls on last and take them off first!
  • Wipe them gently after each use to remove any excess oils or chemicals that may be residing on them
  • Ideally, store them away from other gems as they may be easily scratched or marked by harder stones or metals
  • Avoid chemicals such as perfumes, chlorine, washing up liquid and hairspray

With that, enjoy your next pearl shopping trip and keep this information in mind when you’re scouting for your next exquisite pearl item. If you haven't familiarized yourself with the saltwater pearl, don't hesitate to go over this in-depth guide.

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