Minnesota has a secret that most people don’t know about – tiny diamonds hiding in its glacial deposits. These precious stones were carried here by ancient glaciers from Canada thousands of years ago.

Looking for diamonds in Minnesota isn’t easy if you don’t know where to start. Many folks waste time searching in the wrong spots, getting frustrated, and giving up too soon.

We’ve done the hard work for you. After talking to local rock collectors and geologists, we’ve put together a list of spots where you’re most likely to find diamonds.

These places have already proven lucky for other hunters, and they might be your ticket to finding your own sparkly treasure.

How Diamonds Form 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 Diamonds

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 to start looking for Diamond in Minnesota:

Keystone Quarry

Keystone Quarry sits in Blue Earth County, near Mankato in south-central Minnesota. This active quarry is known among rock collectors for its impressive mineral specimens, particularly its clear quartz crystals.

The best spots to look for minerals are in the quarry’s exposed rock faces and loose material piles. The crystals often form in small pockets or vugs within the limestone.

Many collectors have found success searching through the weathered rock fragments at the base of quarry walls.

The quarry’s location near the Minnesota River Valley adds to its geological importance. This area has some of the oldest exposed rocks in North America, making it interesting for both amateur collectors and geologists.

Paynesville Area

The Paynesville Area sits in central Minnesota’s Stearns County. This region features a mix of farmland and small lakes, shaped by ancient glaciers that moved through Minnesota thousands of years ago.

Local waterways and exposed areas with glacial deposits are good spots to look for rocks and minerals.

Rock collectors often check stream beds and gravel pits in the area. The soil here has lots of small rocks and minerals from far away places, brought here by those ancient glaciers.

While searching for diamonds, you might find agates, jasper, and various colorful stones in the glacial deposits.

Mississippi River

The Mississippi River in Minnesota starts at Lake Itasca and flows south through the state. The river’s course includes both shallow rocky areas and deep gorges, especially near the Twin Cities.

The river’s geology comes from ancient glaciers that moved through Minnesota millions of years ago. These glaciers left behind various rocks and minerals. The river has cut through layers of limestone and sandstone, creating places where gems and minerals can collect.

The areas near Lake Itasca and the Mississippi River Gorge are particularly good for searching for diamonds. The river’s constant movement helps expose new material, especially after spring floods.

The river has a history of producing interesting finds including agates, jasper, and various quartz crystals.

Lake Superior

Lake Superior in Lake County, Minnesota is the largest of the Great Lakes. It sits in the northwest part of Minnesota and stretches into Wisconsin and Ontario, Canada. The lake’s beaches and shores are popular spots for rock collectors.

The lake formed about 1.1 billion years ago during a time of intense volcanic activity. These volcanic events created special rock formations called the North Shore Volcanic Group.

The area is rich in various minerals because of its volcanic past and has many iron and copper deposits. While Lake Superior is most famous for its agates, small diamonds have been found in its glacial deposits.

The best places to look for diamonds are along the lake’s beaches and in stream beds where glaciers left behind mineral deposits thousands of years ago. The lake’s constant wave action helps wash and sort stones, making them easier to spot.

Places Diamonds have been found by county

After discussing our top picks, we wanted to discuss the other places on our list. Below is a list of the additional locations where we have succeeded, along with a breakdown of each place by county.