From engagement rings to fine jewelry, diamonds are so common in our everyday lives that it’s not often that we stop to think about where they came from. But the journey that these little gems make, from formation to the jewelry store, is really quite impressive. How is a natural diamond formed? Where are diamonds found? What are diamonds made of? This precious stone poses numerous questions.
In this article, we’ll explore the main ways diamonds are formed and where diamonds are found. From deep beneath the earth’s surface to a well-regulated lab, you might be surprised by where these dazzling stones are found
Debunking the Coal Myth
You might have heard that diamonds are made from coal. But this is a common myth with no scientific basis. Diamonds are actually made of pure carbon, formed through a natural process that’s been occurring for billions of years. Coal, on the other hand, is a sedimentary rock that’s formed from plant material.
How Are Diamonds Formed?
Simply put, diamond formation occurs when carbon deposits deep within the earth(approximately 90 to 125 miles below the surface) are subject to high temperature and pressure. Some stones take shape in a matter of days or months, while others take millions of years to materialize. In the case of colored diamonds, the color is caused by trace elements interacting during the diamond’s formation. Additionally, it’s almost impossible to determine a diamond’s exact age, but inclusions of specific minerals help geologists to form an estimate.
That being said, most natural diamonds date back millions, if not billions of years. And, interestingly enough, diamond growth isn’t always an uninterrupted process. A rough diamond’s formation can be disturbed due to a change in temperature or pressure. The gemstone could then wait for hundreds or even millions of years for conditions to be suitable for growth to continue.
Methods of Diamond Formation
There are four main processes that are believed to be responsible for nearly all diamond deposit sites found near the earth’s surface – diamond formation in the earth’s mantle, diamond formation in a subduction zone, diamond formation at impact sites, and diamond formation in space.
Diamond Formation in the Earth’s Mantle
Geologists believe that nearly 100% of the diamonds found in diamond mines, and thus used in engagement rings, were formed in the upper mantle and delivered to the earth’s surface by a deep-source volcanic eruption. These volcanic eruptions are credited with creating the kimberlite and lamproite pipes that gemstones are found in.
Geology.com explains these kimberlite pipes and their relation to diamond mining as the following, “Most of these pipes do not contain diamond, or contain such a small amount of diamond that they are not of commercial interest. However, open-pit and underground mines are developed in these pipes when they contain adequate diamonds for profitable mining. Diamonds have also been weathered and eroded from some of these pipes.”
Diamond Formation in Subduction Zones
This second method of diamond formation occurs when rocks are pushed into what geologists call “subduction zones” by tectonic plates and then return to the surface with tiny diamonds. Interestingly, the small rough diamonds formed in subduction zones grow just 50 miles below the earth’s crust at temperatures as low as 390 degrees Fahrenheit(yes, that’s low compared to the usual 2,000 degrees).
Rocks that have journeyed to subduction zones and back are super rare. No known commercial diamonds have been found within them as they are very small and not sold by jewelers. However, an interesting discovery was made as some stones uncovered from subduction zones are believed to contain traces of oceanic crust, appearing as blue diamonds.
Diamond Formation at Impact Sites
Throughout its history, Earth has been subjected to a hit or two from a few asteroids(just ask the dinosaurs). When an asteroid collides with the earth, it produces intense pressure and temperatures, two qualities that are perfect for creating diamonds. This process can be viewed at several asteroid impact sites around the globe, two of the most popular of which are the Popigai Crater in Siberia, Russia and, the Meteor Crater in Arizona.
Diamond Formation in Space
Little green men aren’t the only things floating around in space. NASA researchers have found large amounts of nanodiamonds in some meteorites. Unfortunately, these diamonds are far too small to use for diamond jewelry or industrial abrasives, but they still make for a fun discovery.
What’s more, the Smithsonian found large amounts of tiny diamonds in the Allen Hills meteorite, providing more evidence that space diamonds are indeed a thing.
Lab-Grown Diamonds: A Sustainable Alternative
In recent years, lab-grown diamonds have become a popular alternative to traditional diamonds. These diamonds are created using advanced technology that replicates the natural process of diamond formation. Lab-grown diamonds are made of pure carbon, just like natural diamonds, but they have several advantages. They’re more affordable, sustainable, and environmentally friendly.
How Are Lab-Grown Diamonds Made?
There are two main methods of creating lab-grown diamonds:
- HPHT (High Pressure, High Temperature): This method involves subjecting a diamond seed to intense heat and pressure, mimicking the natural process of diamond formation.
- CVD (Chemical Vapor Deposition): This method involves depositing carbon atoms onto a substrate, creating a diamond crystal structure.
Conclusion
Diamonds are a fascinating gemstone that has captivated humans for centuries. From their formation deep within the earth’s mantle to their creation in labs, diamonds are a true marvel of nature. Whether you’re considering purchasing a diamond or simply interested in learning more about these incredible gemstones, we hope this article has provided you with a deeper appreciation for the world of diamonds.
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