How Diamonds are Made: From Volcanic Mines to Your Jewelry Box

Most everyone knows what diamonds look like.

Their clear, polished stone surface with smooth facets that sparkle in the light are unmistakable.

But it takes a lot of work for diamonds to become the stunning stone desired by so many.

Contrary to popular belief, diamonds are not formed from coal. They’re formed from carbon.

The journey from beneath the earth to our jewelry store is an extensive, yet incredible one.

Diamonds are Made Under the Earth

Genuine diamonds are known as the hardest naturally occurring substance on Earth.

Sought after for hundreds of thousands of years, the process of finding and refining diamonds is a treasure.

Diamonds, unlike rocks, are only formed in specific places within the earth, where three specific conditions are present: great depth, high levels of heat, and massive pressure.

These zones, known as “diamond stability zones,” are commonly found beneath continental plates under the Earth’s surface.

These stunning jewels first begin as carbon, hidden deep within the upper mantle of Earth, approximately 150 km underground. This carbon is exposed to temperatures of 2200 degrees Fahrenheit and is pushed down by about 725,000 pounds of pressure per-square-inch.

The intense heat and pressure work together to change the molecular structure of the carbon to a crystallized state.

The balance of the three elements is so specific that if one of them is not correctly proportioned, there will be no diamond. But instead, a softer substance also based from carbon called graphite will be formed.

This process is no quick feat. It is believed that diamonds have taken billions of years to form into the beautiful gems that they are today.

How do Diamonds Make it to Earth’s Surface?

Diamonds make their entrance on the Earth’s surface through volcanic magma called Kimberlite.

Diamonds that are located within these volcanic pipes are gathered and pushed towards the surface along with other rocks that formed during its eruption.

Once the diamonds are brought up to the crust through Kimberlite, the whole rock structure cools and hardens, encrusting xenolith rocks within it where diamonds are found.

Diamond Mining

Diamonds are also commonly found in Russia, India, Brazil, Canada, China, and the United States.

To mine diamonds, interested parties must first pinpoint the location of the highly valued Kimberlite pipe deposits where diamonds are most likely to be found.

Most of the world’s diamonds are found and harvested from South Africa — Botswana being a main production center.

Once the source of the Kimberlite is located, excavators use explosives to break apart massive amounts of cooled magma and harvest the volcanic ore.

The ore is taken to laboratories where the larger rock masses are broken down into much smaller fragments by large machines specifically created to break down the rocks into small pieces. This process makes the remains easier to sort through in search of the hidden diamonds.

Once the diamonds are found and separated, they are submerged in a chemical solution to break down any lingering rock that may be attached, leaving only rough diamonds.

How are Diamonds Cut & Polished?

Once the rough diamonds are filtered out, they are ready to be cut and polished.

This lengthy process can take weeks to complete and involves choosing the diamond shape, planning how it will be cut, sawing and bruting the diamond.

Finally, the diamond is then polished and shined.

solitary diamond held in silver metal tweezers above jewelry-making tools

Attention to detail is especially important as it determines the end result of the diamond.

After choosing the overall shape of the diamond (oval, pear, round, emerald, etc.), planning the cut of the diamond is one of the most important steps in the process.

Diamond Marking

Here, a Sarin machine is used to produce computer simulations of the rough stone. The blocker then maps out exactly what sections of the diamond will be cut, ensuring that as much of the diamond is used as possible.

The rough stone may be able to yield two smaller diamonds or a larger diamond. The number of diamonds produced is dependent on the size and shape of the rough stone.

When the planning stage is complete, the diamond is ready to be cut.

Diamond Cutting & Shaping

To cut the diamond, the blocker, who is also the lead cutter, must use special tools to saw the diamond to separate it if necessary.

The diamond then undergoes a process called bruting where it is held along the rough edge of the cutting wheel to be shaped.

Once the bruting is finished, the diamond is polished.

Diamond Polishing

Two steps take place during the diamond polishing phase: blocking and brillianteering.

This two-step process requires exceptional precision and patience.

The diamond cutter is used to cut facets into the diamond to create the angles and shape that captures the light.

Then the diamond is placed on a brillianteer and polished on the fine wheel to create the remaining facets, making sure it reflects as much as light as possible. This is important, as clarity and brilliance are two key elements used to determine the value of a diamond.

The diamond, now cut and polished, undergoes final inspection and carat weight is determined.

It can take years for a diamond to become what we know and love — the stone that sparkles and evokes emotions.

Whether it’s a diamond engagement ring, stunning bracelet, or dazzling earrings, each diamond is precious and can and should be cherished for years to come.