The Difference Between Mined And Lab Grown Diamonds
November 22, 2021 • 11 min read • #diamond mining
Nothing speaks class like wearing a diamond. It can start a conversation on fashion, culture and recently — sustainability. In January 2019, Meghan Markle, the Duchess of Sussex attended an event in London with a pair of diamonds earrings. And it did just what most diamonds do — started a conversation. But this wasn't just any pair of diamond earrings. The diamond earrings that Meghan Markle was wearing were lab grown.
Ever since the release of the film Blood Diamond in 2006, the diamond industry has come under a lot of scrutiny about its malpractice concerning ethics, environmental damage and murky supply chains. Since then, the mined diamond industry created the Kimberley Process to ensure that the global supply chain of diamonds would become more ethical. But even with this process, problems remain. Sustainability has become a growing talking point with a diamond market research firm VMEye suggesting that up to 70% of millennials would consider buying a lab grown diamond for an engagement ring.
So how do lab grown diamonds compare to mined diamonds? To answer that question we first need to understand how traditional diamonds are formed and mined in the first place.
How Are Diamonds Formed?
A mined natural diamond is a form of crystallised carbon that is created around 160km below the Earth's surface over millions of years. Both extreme heat and pressure push the carbon atoms together so densely that they form a diamond. In terms of temperature, the carbon faces around 1100°C and around 13 tons per centimeter.
Because we can't drill down 160km into the Earth's crust into the mantle, diamonds reach the surface through deep-seated volcanoes that have happened over the Earth's history. No eruption in recent times has resulted in diamonds reaching the surface. It most likely happened when the Earth was hotter. But it doesn't rain diamonds. Instead, the diamonds are held within Kimberlite pipes. And the diamonds need to be separated from the rock.
Only very specific types of volcanoes bring up diamonds to the surface. These are called Kimberlite volcanic eruptions. If the molten lava moved too slowly towards the Earth's surface, the diamond turns into graphite along the way. With the eruption happening quickly, the carbon gets locked into place forming the crystalline structure.
Diamond is such a strong material because each carbon atom has four bonds with four other carbon atoms. The extreme heat and pressure ensure a locked covalent bond between each carbon atom creating a crystalline structure. One carat of diamond contains billions of carbon atoms that lock into place in a very specific way.
Diamonds coming from the Earth is not guaranteed in a Kimberlite volcano. Diamonds may start to grow under the specific conditions already mentioned but then something may change. A change in conditions or an introduction of other elements can disrupt the development of the crystalline structure. The diamond would need to start growing again and this can take millions of years.
After a Kimberlite volcano, diamonds come closer to the Earth's surface. But because these volcanoes happened millions if not billions of years ago, they start to work their way back towards the Earth's mantle. Consequently, they can be mined.
How Are Diamonds Mined?
There are three ways that diamonds are mined from the Earth: pipe mining, alluvial mining and marine mining.
1 Pipe Mining
There are two types of pipe mining: open-pit and underground mining.
a) Open-Pit Mining
Open-pit mining is the process of removing layers of sand and rock found just above the kimberlite. Once diamond is found, a pit is formed and the rock is broken by blasting. Excavators then start to load up the rock for it to be crushed and then the diamonds are extracted.
b) Underground Mining
Similar to coal mining, tunnels are dug beneath the Earth's surface. Two layers of tunnels are formed. On the level closest to the Earth (level 1), blasting is done and Kimberlite then falls into the deeper layer (level 2) through a lining of funnels between the two layers. Similar to open-pit mining, excavators then start to load up the rock for it to be crushed and the diamond to be extracted.
Note, it is a myth that the carbon in coal mining can turn into diamond. Coal mining originates from plant debris and fungi. The impurities make it extremely unlikely for it to be turned into diamonds. Furthermore, the carbon in coal doesn't go as deep as the carbon in diamond so it doesn't face the same temperature and pressure.
2 Alluvial Mining
Kimberlite pipes do not always go back towards the Earth. Sometimes they remain on the surface and get eroded by wind and water. These are typically then carried downstream. The kimberlite pipe begins to erode and leave rough diamonds.
For alluvial mining to be financially feasible, mining companies build large walls to collect the water.
Diamonds are found on the gravel layer alongside mud, clay, other rocks and plants. Alluvial mining has destructive implications for the environment as ecosystems are disrupted to find diamonds, just like with pipe mining.
3 Marine Mining
Marine mining is extracting diamonds from the seabed. The earliest instance of marine mining was shore divers collecting diamonds off a shallow seabed.
Today, diamond miners use special ships with crawlers that remove gravel off the seabed through hoses (disturbing the natural ecosystem along the way). If the diamonds are below the surface, the miners can also use a large drill.
Because the boats need to be space-efficient, they need to extract as much diamond as possible and leave as much sediment behind. So the hoses pull up the seabed and on the ship, the diamonds are extracted. The rest is then dumped back into the sea. The seabed isn't just "sediment." It typically includes aquatic life. Disrupting this disrupts the natural ecosystem.
Scientists have warned against this type of ecological destruction because no one really knows how long it will take for an ecosystem to regenerate — if ever.
Sustainability of Mined Diamonds
The three steps so far discussed is only part one of the diamond mining process. There are five more processes that still need to happen.
- Crushing of the rock
- Cyclonic separation (separating the diamond from rock)
- Recovery of diamonds
- Cleaning, weighing and packaging
Furthermore, for one carat of diamond, around 160kg of CO₂ is produced. The mined diamond industry will point to report that they commissioned through the Diamond Producers Association claiming that lab diamonds have a carbon cost of 510kg of CO₂ per polished carat (note that this can be seen as a biased source).
Nonetheless, what they don't tell you is that of the diamonds that are mined, only 20% have retail value. Many of the diamonds that are mined are not fit for retail, and even if they are, they are sold extremely cheaply. They are called brown diamonds (very low on the colour spectrum on the 4Cs). This should multiply the cost of producing one carat to a lot higher for each carat of diamond.
If you are looking for a climate positive diamond, look no further than Four Words. Not only do we offset our carbon, we help offset the mined diamond industry's too.
How Are Lab Grown Diamonds Made?
There are two processes that lab grown diamonds are made through:
- High-Pressure High Temperature (HPHT) and;
- Chemical Vapor Depositation (CVD).
Process 1: High-Pressure High Temperature (HPHT)
The HPHT process mimics the processes that occur naturally with naturally formed diamonds. It starts off with carbon chains that are not yet fully crystallised (often called 'premature diamonds' or 'diamond seeds' which are carbon chains of typically graphite) and then applying the same types of temperature and pressure as found deep within the Earth.
There are five main stages to an HPHT diamond:
The diamond seed is placed in a specifically designed press or 'containment cube.' This is done by a highly trained gemologist to ensure that the seed will indeed turn into a crystalline structure.
The containment cube undergoes heating and of about 1500°C and around 12 tons of pressure per centimeter. These are very similar conditions found deep in the Earth's mantle. Catalysts are also added such as iron, nickel or cobalt to lower the amount of energy and pressure required to complete the reaction from diamond seed to diamond crystal.
Any metal in the carbon seed dissolves away and leaves a high purity carbon source. This becomes the foundation of the diamond.
Carbon atoms precipitate (rain down) on the diamond seed crystal and the diamond itself starts to grow.
Within a few weeks, the diamond crystal structure is fully formed. It is then cool, cut and polished by a diamond cutter.
It is important to note that HPHT are not 'fake' diamonds. They are natural diamonds. The process is exactly the same as naturally forming diamonds. The only difference is that the HPHT process happens in a lab and not below the ground.
Process 2: Chemical Vapor Depositation (CVD)
Another method for creating lab grown diamonds is the chemical vapor deposition process. In this process, diamonds are grown from a hydrocarbon gas mixture (like methane) where it undergoes an increase in temperature and pressure in a vacuum chamber. There are six key steps to creating a lab grown diamond from the CVD process:
Just like with the HPHT process, diamond seeds are placed in a diamond growth chamber.
Before there is an increase in temperature and pressure, the chamber is filled with a hydrocarbon gas mixture.
Then the chamber is heated to around 1,000°C
A microwave beam causes the carbon to precipitate out of the hydrocarbon gas mixture (which is now a plasma cloud) and "rain down" on the diamond seed which then starts to turn into a crystal. The hydrogen in the hydrocarbon gas etches off any non-diamond carbon.
The diamonds are removed every few days to have the top of its surface polished. This ensures that any non-carbon diamond is removed so it can continue to grow.
This stop-start nature happens a few times and it takes about three to four weeks to go from diamond seed to a diamond that is ready to be cut and polished.
The CVD method was developed in the 1980s and unlike HPHT, it does not require as high pressures which means it can be done with consuming less energy. And while the process of coming to a polished diamond is not the same as the one found in nature, the outcome of a diamond is exactly the same — optically, physically and atomically exactly the same as HPHT and the natural Earth process.
Lab grown Diamonds Are The Same As Mined Diamonds
As we have seen throughout the formation of natural and lab grown diamonds, they are very similar (especially HPHT). The process is roughly the same. The only difference is that the natural process occurs below the ground while lab grown diamonds are formed above the ground. This results in the diamonds being optically, physically and atomically exactly the same as mined diamonds.
In July 2018, The US Federal Trade Commission updated the Jewelry Guides. It changed the way diamonds could be described and was opposite to what De Beers advocated for in 2016.
The new guidelines stated that lab grown diamonds are equivalent to "natural" diamonds and "if a marketer uses 'synthetic' to imply that a competitor's lab grown diamond is not actually a diamond, it would be deceptive.' This means that lab grown diamonds are diamonds — just as mined diamonds are.
In 2019, a third party diamond certification lab, The Gemological Institute of America dropped the word 'synthetic' in their grading reports and certification and replaced it with lab grown instead.
We often have to make a trade-off in either price or quality when making a sustainable choice. But for diamonds, you can choose something that is more sustainable, higher quality and more cost effective than the alternative. Diamonds are forever, but the environmental destruction doesn’t need to be.
Get in touch today to get started on your diamond journey.