If you’re any sort of diamond enthusiast you’ve likely started to research diamonds, what they are, how they’re made, and their general quality inspection guidelines. Then you’ve probably remembered something you’ve heard somewhere or read somewhere, or maybe seen in a cartoon: diamonds are made of coal. Are they really though ?
Do diamonds come from coal ? Can you turn any piece of coal into a diamond ? Does it work with peanut butter too ? Let’s talk about this, see if there’s any truth to any of it.
Do diamonds come from coal ?
No, diamonds do not come from coal and do no contain any trace amounts of coal. This is because diamonds are pure 100% carbon, a single mineral that has been fused together through intense heat and immense pressure, both sustained for a long period of time. Diamonds form at a far deeper level than coal, and they are far older than any piece of coal.
To better explain this, let’s take a look at what coal is, what diamond is, and compare the two more thoroughly.
What is coal ?
Coal is a solid rock-like material that is originally formed from dead plant matter, and now only contains hydrogen, sulfur, oxygen, and carbon. This material comes from the time when the Earth had plenty of forests, higher oxygen levels, and animal life was just beginning. Millions of years ago, dead plants were trapped in mud or acidic water, which did not allow them to decay. Instead, the plants were compacted as time went on, and turned into coal. This is an overly simplified version of these events.
The process that formed coal originally took place on the Earth’s surface, but as tectonic plates shifted, volcanoes erupted, and the soil moved about, most coal deposits shifted underground. It’s this underground shift and the accompanying heat that helped finalize coal’s transformation from peat to actual coal. It added more and more pressure, which was a vital step.
Coal is made from plants that covered the Earth from approx. 300 million years ago to as early as 66 million years ago. That is when the meteor hit, wiped out most of the animal and plant life, and changed the atmosphere.
What are diamonds ?
Diamonds are a material made entirely of carbon, formed at a very deep level in the Earth’s mantle and brought closer to the surface by volcanic eruptions and tectonic plate shifts.
Diamonds require immense heat and pressure, both sustained for a very long time, in order to form. The carbon in diamonds is not the byproduct of something else, such as decaying plants or animals, it is pure carbon that has been trapped as the Earth was formed as a planet. Diamonds are just a bit younger than our planet, most of them dated at 1-3.5 billion years old. The Earth itself is about 4.54 billion years old, give or take 50 million years.
Read also: Is Lapis Lazuli A Gemstone ?
Why diamonds are not made of coal
Diamonds form at a much lower level in the Earth’s mantle than coal. Diamonds formed at levels that are 150-250 km deep, while coal formed on the Earth’s surface (peat) and was then only buried a few kilometers deep, later turning into coal. This is further supported by coal’s much younger ‘age’, compared to diamonds.
Coal is made of peat, which is made entirely of dead plant matter, that used to cover the Earth at various points in prehistoric eras. The youngest piece of coal is about 66 million years old, which did not give the Earth enough time to bury coal deeper within its layers.
Meanwhile the youngest diamond is 1 billion years old, with most diamonds falling in a range between 1 billion and 3.5 billion years old. They were formed from pure carbon that was trapped within the Earth as it formed as a planet. So diamonds are far, far older than coal.
And finally, if you were to analyze a piece of coal an compare it to a diamond, you’d notice that coal is mostly carbon but also contains hydrogen, oxygen, and sulfur. Coal only contains carbon.
Can you put pressure on coal to turn it into diamond ?
No, coal cannot be turned into a diamond, no matter the pressure or heat you apply to it. The reason is that you still have a higher percentage of hydrogen, oxygen, and sulfur that would not allow the diamond’s crystal lattice to form properly. The result would be anything but a diamond.
Aside form this, the equipment needed to subject a piece of coal to such high pressure and heat for an extended time would be very difficult to come by. No, if you want to make a diamond out of something that is not a diamond, you need pure carbon atoms. And that’s essentially the way lab-grown diamonds are made.
Lad-grown diamonds are becoming commonplace
This all makes diamonds sound like very, very precious, complex gems that are a real treat to have on your engagement ring. And, in a way they really are. But this is about to change, as more and more diamonds are now lab-grown. This is a process that still takes immense heat and pressure, and it takes a lot of time, but it does make diamonds more easily accessible and it means the diamonds are not mined in an inhumane way.
It used to be that diamond mining was essentially a form of slavery and exploitation, with people worked to death and the diamonds then sold for weapons and used as a means to start massive conflicts in Africa. The the Kimberley process became commonplace, and now all mined diamonds must show a certificate that enables you to trace the diamond all the way back to the original mine.
Still, the only truly conflict-free diamond is the one grown in a lab, that does no involve any mining or leave room for any possible human exploitation.
The downside to lab-grown diamonds is that they’re, well, not natural diamonds, despite them being made of the exact same thing as a real diamond. So natural diamonds come at a premium price, simply for being natural.
The upside to lab-grown diamonds, aside from lower prices, is that you can easily find them in the color, clarity, cut, and carat weight you’re looking for.
Are diamonds rare ?
Natural diamonds are not truly rare, but the supply was greatly restricted in the late 1800s and early 1900s. As such, diamonds have come to be perceived as rare, and precious, and prestigious.
What is truly rare is the right color and clarity for jewelry diamonds. Diamonds that are graded D (as white as they get) and Flawless or VVS1 are truly rare, as diamonds are usually a bit yellow tinted and have some inclusions in them.
Diamonds that have quite a few inclusions in them – such as salt and pepper diamonds – have become more and more popular in the past few years. White milky diamonds are also included diamonds, and so are black diamonds.
So, in the end, diamonds as a gemstone are not truly rare. The classic perfectly clear and perfectly white diamond is far rarer, but its included siblings are getting more and more popular.
I’m the main author for jewelrymaterialguide.com. I started this site after we did tons of research before our wedding and noticed that there is information about rings, jewelry, and so on that is really hard to find on the internet.