From Idaho to North Dakota, and from Wyoming to British Columbia, Montana is a great place for diamond finders. This treasure state holds more than just its famous sapphires.

We’ve done the legwork to bring you the top spots for diamond hunting in Montana. Our carefully researched list will save you time and effort. No need to wander aimlessly.

We’ll guide you to the most promising locations for your diamond quest. Get ready to explore Montana’s hidden gems!

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

Across the state, there are several promising spots where diamond hunters can commence their quest. From the rugged mountains to the winding creeks, Montana offers a variety of areas that show potential for diamond discoveries.

Greenhorn Gulch

Greenhorn Gulch is nestled in the southern part of Madison County. This picturesque area is part of the Greenhorn Range, characterized by its rugged mountains and stunning landscapes.

The unique geological features of Greenhorn Gulch, with elevations reaching up to 8,622 feet, create ideal conditions for mineral deposits.

Gemstones can often be found in the gravels and creeks that meander through the area, especially along the slopes of the mountains.

Adventurous seekers can explore these natural deposits, where the combination of erosion and sedimentation reveals treasures waiting to be discovered.

Nelson Hill

Nelson Hill, located in the northwestern part of Montana’s Glacier County, is a hidden gem for those seeking diamonds.

This site is significant as diamonds were discovered here in the late 1800s, making it a noteworthy location for gem enthusiasts.

The area’s unique geology, shaped by ancient volcanic activity, has created conditions that once favored diamond formation.

At Nelson Hill, you can explore gravel deposits and creek beds, which are prime spots for finding these precious stones. The warm-summer humid continental climate contributes to the weathering processes that can reveal hidden treasures.

Missouri River

The Missouri River in Lewis and Clark County flows through the north-central part of the state, offering a unique opportunity for diamond enthusiasts.

In 1990, a jogger discovered a 14-carat uncut diamond, southwest of Great Falls close to the town of Craig. This diamond later referred to as the Lewis and Clark diamond was sold for a price of $80,000.

The river’s gravel bars and riverbanks are known for their abundance of agates, jasper, and petrified wood, which are more commonly found in this region.

The Missouri River’s historical significance, as part of the Lewis and Clark Expedition, adds to its allure for rockhounding enthusiasts. After periods of high water flow, exploring the gravel bars and riverbanks can yield interesting finds.

Grasshopper Creek

Grasshopper Creek, located in the southwestern part of Montana in Beaverhead County, is a hidden gem for those seeking diamonds.

Nestled near the historic ghost town of Bannack, this picturesque creek flows through a landscape rich in geological history, shaped by the gold rush era.

The area is characterized by sedimentary rock formations, which have eroded over time, creating ideal conditions for rockhounding enthusiasts.

Gemstone hunters can explore the gravel bars and creek bed, where the water has naturally deposited various minerals, including diamonds. After heavy rains, these spots are particularly promising for finding interesting stones.

Homestead Kimberlite

Nestled in the heart of Montana’s Grassrange area, the Homestead Kimberlite is a geological marvel that has captured the attention of diamond enthusiasts worldwide.

This kimberlite pipe, a rare volcanic rock formation, is situated in Prairie County and holds the distinction of being the site of Montana’s first in-situ diamond discovery.

What sets Homestead Kimberlite apart is its unique geological composition. The pipe is surrounded by various other volcanic rocks, including aillikite, alnoite, carbonatite, and monchiquite, indicating a complex history of deep mantle processes.

The site is also renowned for its upper-mantle xenoliths, with some of the largest known garnet peridotite xenoliths in North America.

For those seeking to uncover their own diamond treasures, the Homestead Kimberlite offers a chance to explore and potentially find diamonds embedded within the kimberlite rock itself.

Places Diamond has been found by county

Following our discussion of the top selections, we’d like to explore the other noteworthy locations on our list. Below, you’ll find a compilation of additional sites where we’ve had positive experiences, complete with a county-by-county breakdown for each one.