It is possible to find pearls in lakes, but it is very rare. Pearls form inside certain species of freshwater mussels and clams when an irritant like a piece of sand gets inside their shell. In response, the mollusk secretes a fluid called nacre to coat the irritant. Over time, layer upon layer of nacre coats the irritant, eventually forming a pearl. Most natural freshwater pearls form in mussels and clams living in rivers and streams that feed into lakes. However, pearls can also form rarely in mussels living in the lake itself. So while difficult, it is possible to find a pearl produced by a freshwater mollusk while swimming or diving in a lake.
Where are freshwater pearls found?
Most natural freshwater pearls that end up in lakes originally formed inside freshwater mussels and clams living in rivers and streams upstream of the lake. The most common freshwater pearl-producing mollusk species in North America include the Eastern Elliptio, Purple Wartyback, and Mapleleaf mussels. These thick-shelled mussels live burrowed in the gravel and sand of riverbeds across central and eastern North America.
When an Eastern Elliptio, Mapleleaf, or other mussel forms a pearl, the pearl remains trapped inside its shell until the mollusk dies. When the mussel dies, its shell eventually opens, releasing the pearl into the surrounding riverbed. From here, river currents wash the loose pearl downstream. In many cases, these free freshwater pearls wash all the way downstream into the lakes and reservoirs fed by these rivers. This is one way freshwater pearls end up in lakes – by originally forming in upstream river mussels, then getting carried downstream into the lake after the mussel dies.
Do mussels in lakes also produce pearls?
While less common, pearls can also form rarely inside living mussels in the lake itself. In North America, most natural lakes do not have a significant freshwater mussel population. However, some lakes, like the Great Lakes, have diverse mussel beds containing dozens of different mussel species. Most of these are smaller thin-shelled mussels not prone to pearl formation. But a few thick-shelled species like the Plain Pocketbook mussel can produce pearls and live in lakes.
For a pearl to form inside a living lake mussel, a couple unlikely events have to happen. First, the mussel needs to get an irritant like a grain of sand inside its shell between its body and mantle. This is uncommon as mussels carefully filter particles from the water before ingesting them. But it can happen occasionally if a sand grain gets in via an open siphon.
Once an irritant is inside its shell, the mussel then has to react by secreting nacre to coat it. Some mussels simply eject the irritants instead of coating them. Even when it does get coated, the resulting pearl is usually tiny, around 1-2 mm. So while rare, living mussels can produce small pearls in lakes on occasion. These pearls may then be released if the mussel dies, or remain trapped inside the shell.
Where to search for pearls in lakes
Knowing where pearls originate can help narrow down the best areas to search in a lake:
- Upstream river inlets – Many pearls form in upstream river mussels, then wash into the lake when the mussels die. Searching the gravel beds around upstream river inlets can turn up pearls that have freshly washed in.
- Known mussel beds – If a lake has extensive freshwater mussel beds, especially of thicker shelled species, search amongst them. Feel for hard round pearls hidden in the sediment beneath shallow mussel beds.
- Shallow gravel and sand beds – Pearls are dense and tend to sink into gravel and sand sediments. Wade or dive to feel through gravel and sand beds in 1-6 feet of water near shore.
- Nearby dams – Dams trap pearls washing downstream. Search just below dam outflows where pearls often collect in eddies and gravel beds.
Focus on areas less than 10 feet deep with slow currents and good visibility. Searching deeper water makes finding pearls far more difficult.
Searching techniques
Several techniques can help locate pearls scattered across lakebeds:
- Wading – For shallow areas under 4 feet deep, wading allows feeling through gravel and sand beds with your feet and hands.
- Snorkeling – Use a mask and snorkel to search deeper areas while swimming at the surface.
- Scuba diving – Scuba gear opens access to deeper underwater areas with good visibility.
- Raking – Drag a rake with short flexible tines across bottom sediments to feel for small hard objects.
- Sifting – Scoop or suction sediment into a sieve to look for pearls and shells.
Work systematically covering small search areas thoroughly. Look under mussel shells and rocks for trapped pearls. Carefully sift through gravel and shell fragments feeling for hard round shapes. Keep a close eye out for the glint of a small pearl washed clean by wave action.
Identifying pearls
Natural freshwater pearls are difficult to identify. They lack the high luster of mass-produced freshwater pearls. Instead they often look like small misshapen yellowish or brownish beads. Distinguishing pearls requires looking for a few key characteristics:
- Luster – Natural pearls reflect light faintly rather than shining brightly. But they do have a gentle surface lustre.
- Surface – Examine the surface for concentric ring-like growth lines. These are created by nacre deposited in layers as the pearl grows.
- Shape – Pearls are rarely perfectly round or smooth. Natural pearls tend to be irregularly shaped grains or blobs.
- Weight – The high density of nacre makes even small natural pearls feel relatively heavy for their size.
- Color – Natural colors like white, yellow, brown and purple predominate. Black pearls also form occasionally.
- Flaws – Most natural pearls contain surface flaws like pits, bumps and depressions.
With experience, the appearance, feel and weight of a genuine pearl becomes more apparent. Any pearls showing high luster, perfect shape or vivid non-natural colors are likely fakes or enhanced cultured pearls.
Are freshwater pearls valuable?
Most natural freshwater pearls are quite small, from around 1 to 6 mm. Larger pearls over 10 mm are rare. Size greatly impacts value, with bigger pearls commanding progressively higher prices.
In addition to size, pearl value depends on:
- Shape – Symmetrical, spherical pearls are most valuable. Irregular blobs are least valuable.
- Surface – Clean surfaces are preferred. Major pits, bumps and flaws reduce value.
- Color – White and pink tones are most desirable. Yellow, brown, purple are still valuable in good sizes.
- Luster – Peals with excellent luster are worth substantially more.
Very small 1-2 mm pearls have essentially no market value. But exceptional large natural freshwater pearls over 10 mm can be worth over $1,000. Most loose lake pearls fall somewhere in between based on their individual size and quality. Full matched strands are ultimately the most valuable.
Are pearls common in lakes?
Natural freshwater pearls form rarely in only a tiny fraction of mussels, just like natural gems form in a small fraction of rock ore. The odds of any individual mussel producing a pearl are extremely low. And lakes offer relatively limited mussel habitat compared to vast river ecosystems. So while native mussels can produce pearls in lakes, the overall numbers of pearls are very low.
Out of the thousands of common thin-shelled mussels living in a large lake, perhaps only a dozen or two thicker shelled pearl-producing mussels may be present. Each year, only one or two of these mussels might actually form an insignificant tiny pearl. This makes pearlsAnything bigger than a few millimeters extremely scarce. Finding a valuable pearl over 5 mm requires thoroughly searching hundreds or even thousands of mussels. So pearls can be found in lakes, but only rarely with considerable effort.
Regulations on collecting pearls
Before searching for pearls, make sure you follow all state and local regulations. Nearly all native freshwater mussel species are now protected under state law, with penalties for disturbing their habitats. State fishing licenses may be required to search underwater for pearls. And be sure you’re only accessing public areas open to recreational pearl hunting – private property and nature reserves are off limits.
When you do look for pearls, take care to return mussels and sediments back to their original position. Never remove live mussels from the lake. Follow principles of ethical pearl hunting by minimizing your impact on the lake ecosystem. With care and respect for nature, searching for natural pearls can be an enjoyable outdoor recreational activity. Just don’t expect to readily find the next pearl of great price – that will take a good portion of luck!
Conclusion
While rare, natural freshwater pearls can occasionally be found in some recreational lakes. Most originate from mussels in upstream rivers, eventually getting washed downstream into the lake. But pearls can also form rarely inside live mussels inhabiting the lake itself. The best areas to search are upstream river inlets, shallow mussel beds, gravel sediments, and just below dams. Carefully feeling through gravel and sifting sediments offers the best chance of locating a loosely embedded pearl. If you do find one, its value will depend greatly on quality factors like size, shape, surface, color and luster. Small low-quality pearls are common but worthless, while large fine ones are extremely scarce but valuable. With persistence and an ethical approach focused on protecting fragile mussel habitats, lake pearls present an exciting treasure hunting challenge.