Diamonds are one of the most popular choices when it comes to precious gemstones, and are known as a symbol of love and durability, but what is it exactly that causes diamonds to be so hard wearing and how are they formed? Let’s start at the very beginning…
What Are Diamonds Made Of?
Diamonds are made up of one single element – Carbon. These beautiful gemstones are a solid form of carbon atoms, bonded together under intense high pressures and temperatures. These conditions cause the atoms to be in a close enough proximity to bond in 4 covalent bond structures. Due to these extreme conditions, the carbon atoms form extremely strong bonds, with each singular carbon atom bonding with four other carbon atoms. It’s these incredibly strong bonds which gives diamonds their extreme durability and why they are one the hardest naturally formed substances on Earth.
How Are Diamonds Made?
Very deep down inside the Earth’s crust, about 150 – 200 km below surface level, temperatures are extreme and average at around 900 – 1.300 degrees celsius. Not only is it unfathomably hot, but this deep into the earth’s crust presents a pressure that is around 50,000 times that of the pressure on the Earth’s surface – ranging from 45 – 60 kilobars! As mentioned earlier, these extreme conditions cause the carbon atoms to bond together and gradually crystallise to form diamonds, and it’s estimated that the majority of these diamonds were formed from around 1 billion to 3.5 billion years ago.
*named after ‘Kimberley’, a town in South Africa where the first diamonds were found in this type of rock*
The extreme conditions that resulted in the formation of diamonds, are the same conditions that are responsible for the formation of both molten lamproite and kimberlite (AKA magma) in the Earth’s upper mantle. These intense conditions cause expansion at very rapid rates creating a domino effect, in turn bringing up all diamonds formed billions of years ago up to the Earth’s surface. Due to the rapid expansion rates, the magma erupts and the extreme speed at which this happens causes it to take shape as a ‘pipe’ as it’s forced to the Earth’s surface. As this magma gradually cools, it solidifies into vertical ‘pipe’ structures to form Kimberlite. Approximately 1 in every 200 kimberlite pipes contain ‘gem quality’ diamonds, yet it is these kimberlite pipes which are said to be one of the most significant sources of diamonds to date!