From the Mississippi River on the west to the Wabash River on the east, and from Wisconsin’s southern border to Kentucky’s northern edge, Illinois is a state rich in natural wonders.

If you’re eager to uncover these hidden treasures, you’re in the right place. We’ve done the hard work for you, scouring the state to find the best diamond-hunting spots.

Our research will save you time and energy, ensuring you focus on the most promising locations. Read on to discover the only four places to find diamonds in Illinois.

How Diamond Forms Here

Diamonds form deep within the Earth, about 90 to 200 kilometers below the surface, where conditions are extreme.

Here, carbon atoms are subjected to intense heat—around 900 to 1,300 degrees Celsius—and immense pressure, about 45 to 60 kilobars. This environment causes the carbon to crystallize into diamond structures over millions to billions of years.

Over time, erosion and weathering expose these stones, making them accessible for mining.

What’s amazing is that each diamond’s journey from deep within the Earth makes it unique, with its own shape, size, and clarity.

The Types of Diamond

Diamonds are classified into various types based on their structure and color. Here are some of the popular types of diamond:

Black Diamond

Black diamonds, also known as carbonados, are truly one-of-a-kind. Unlike their clear cousins, these stones are opaque and have a matte finish.

They don’t sparkle in the traditional sense but have a unique, mysterious charm all their own.

What makes black diamonds special is their age and formation. Most are believed to be 2.6 to 3.2 billion years old, making them some of the oldest gemstones on Earth.

Their dark color comes from numerous inclusions and the presence of graphite or other minerals.

Recently, a massive black diamond called “The Enigma” made headlines. Weighing 555.55 carats, it showcases the growing interest in these unusual stones.

Yellow Diamond

Yellow diamonds shine with a vibrant, sunny hue. Their color ranges from light yellow to deep, intense shades.

This beautiful color comes from nitrogen atoms in the diamond’s structure. These atoms absorb blue light and reflect yellow, giving the stone its unique appearance.

Unlike clear diamonds, yellow diamonds are graded based on their color intensity. The deeper and richer the yellow, the more valuable the stone. This grading system is different from the one used for colorless diamonds.

Blue Diamond

The color of the blue diamond can range from a soft, icy blue to a deep, vivid shade. This striking blue comes from boron in the diamond’s crystal structure. It’s a rare occurrence in nature, making these diamonds very uncommon.

One cool thing about blue diamonds is how they react to ultraviolet light. Many of them show a unique glow called fluorescence. This can make their color even more impressive under certain lighting.

Blue diamonds have some famous examples. The Hope Diamond is probably the most well-known. It’s known for being the largest diamond weighing 45.52 carats. It’s current value is estimated to be US$200–350 million.

Red Diamond

Red diamonds are incredibly rare and highly prized. Their distinct red color comes from structural imperfections in the diamond’s crystal lattice, not from chemical impurities like other colored diamonds.

These diamonds are so rare that very few have ever been found. Each discovery of a red diamond is a significant event in the gemstone world.

Their rarity makes them even more valuable than pink or blue diamonds, which are already considered extremely precious.

Some famous red diamonds have captured public attention. The Moussaieff Red from Brazil and the Kazanjian Red Diamond from South Africa are notable examples.

In 1987, a red diamond (Hancock Diamond) sold at auction for a record-setting $927,000, highlighting the extraordinary value placed on these rare gems.

Pink Diamond

Pink diamond’s color can be a soft, delicate pink or a deep, vivid rose. What’s interesting is that scientists aren’t entirely sure why they’re pink. It’s thought to be due to a twist in their crystal structure, not because of any specific element.

These diamonds are incredibly scarce. For every million carats of rough diamonds mined, only one carat might be a pink diamond. This rarity makes them highly prized by collectors and jewelers.

Even small pink diamonds can be worth a lot because of their rarity. They’re often used in high-end jewelry, where their unique color makes a big impact.

Green Diamond

Green diamonds are some of the most unusual and unique colored diamonds. Their color can range from a light mint to a deep forest green

What makes them special is how they get their color. It’s not from a chemical element, but from exposure to natural radiation over millions of years.

This natural coloring process is incredible. It happens when diamonds are near radioactive rocks deep in the earth. The radiation changes the diamond’s crystal structure, creating the green color.

Green diamonds often show unique light effects. Some might have a strong glow under certain lights, adding to their allure.

What Rough Diamonds Look Like

Rough diamonds can be challenging to identify. Here are a few proven techniques that will make it easier for you to identify the rough diamond:

Check for a Glassy or Waxy Luster

One of the most noticeable features of a rough diamond is its luster. Uncut diamonds often have a glassy or waxy appearance.

This is because the rough surface scatters light differently than a smooth, cut surface.

Look for an Octahedral Shape

Rough diamonds typically take on an octahedral shape, which resembles two pyramids joined at the base. This shape is a result of the diamond’s cubic crystal structure.

However, not all rough diamonds will have a perfect octahedral form, as they can be distorted or irregular due to natural forces during formation.

Assess the Density and Weight

Diamonds are known for their density and weight. A rough diamond will feel heavy for its size compared to other stones.

You can test this by holding the stone in your hand and comparing it to a known non-diamond.

Look for a Crystalline Texture

When examining a rough diamond, you may notice a distinct crystalline texture on its surface.

This is due to the diamond’s atomic structure and can help distinguish it from other minerals or synthetic stones.

A Quick Request About Collecting

Tips on where to look

Once you get to the places we have listed below there are some things you should keep in mind when you’re searching:

Look in Sedimentary Rocks

Sedimentary rocks are a great place to start. These rocks form from layers of materials that have settled over time.

Diamonds can be found in these layers. Look for areas where the rock has been worn down or eroded. This is where diamonds might be exposed.

Explore Riverbeds

Rivers are another excellent spot. Over time, water carries diamonds downstream. Look for gravel beds in rivers. These spots can hold diamonds that have been washed away from their original location.

Pay attention to bends in the river. These areas often collect heavier materials, including diamonds.

Check Old Mining Sites

Old mining sites are worth exploring. Many diamonds were left behind during past mining activities.

Look for areas where mining was done in the past. Even if the site is no longer active, it can still be a good place to find hidden gems.

Investigate Hillsides

Hillsides can also be promising. Erosion can expose diamond-bearing rocks. Look for loose soil or rock on slopes.

These areas may reveal diamonds that have been pushed to the surface over time.

Some Great Places To Start

Here are some of the better places in Illinois to start looking for diamonds. These locations offer unique opportunities for gem enthusiasts to search for and potentially discover these precious stones.

Fayville

Fayville is situated along the Mississippi River, just south of Thebes in Alexander County.

The streambeds in Fayville have been shaped by the river’s natural flow, which can transport diamonds from their original locations, making it a prime spot for gem hunting.

The combination of glacial deposits and sedimentary layers creates a favorable environment for diamonds to be found. The erosion process exposes gravel and sand, revealing hidden treasures after heavy rains.

The thrill of searching in such a scenic spot, along with the area’s geological characteristics, makes Fayville a significant destination for those seeking to find diamonds in Illinois.

Mount Vernon

Mount Vernon, located in Jefferson County, is part of the ancient geological formations known as the Illinois Basin, which has a rich history of mineral deposits.

The unique combination of volcanic activity and sedimentary processes in this region creates ideal conditions for diamond formation.

The area’s soil is often rich in minerals, and the presence of kimberlite pipes—volcanic structures that can carry diamonds from deep within the Earth—makes it a promising site for finding these precious stones.

Local enthusiasts often search along riverbanks and in gravel pits, where erosion may expose hidden treasures.

Macomb Area

Macomb is located in western Illinois, about 75 miles southwest of Peoria. This area boasts a rich geological backdrop, shaped by ancient glacial activity and sedimentary rock formations.

The unique combination of these elements creates an environment where various gemstones can be found.

The region’s history includes volcanic activity that may have brought gemstones closer to the surface, making it an exciting spot for discovery. Local rivers and streams often wash away soil, revealing hidden treasures along their banks.

In addition, the diverse landscape offers a variety of terrains to explore, from wooded areas to open fields, increasing the chances of finding unique stones.

Woodlawn Area

The Woodlawn Area is a small village in Jefferson County. This region is known for its unique geological features, particularly its ancient volcanic activity, which has created the right conditions for diamond formation.

What makes the Woodlawn Area ideal for diamond hunting is its accessibility and the presence of gravel deposits along the banks of the nearby creek that have been weathered over time.

The local landscape, shaped by glacial movements, also contributes to the concentration of these precious stones in the creek bed and along the riverbanks.