Pink diamonds, one of the planet’s rarest jewels, have gained popularity in recent years because of their striking colour, and captivating nature. “Everybody’s talking about them. Everybody loves them,” according to Jeffrey Post, a curator at the National Gem and Mineral Collection of the Smithsonian’s National Museum of Natural History, Washington, DC. These pink gemstones have become symbols of elegance, romance and luxury.
How Are Pink Diamonds Formed?
- Evidence shows that pink diamonds are formed deep, deep down from inside the Earth’s mantle, in very extreme conditions with specific temperatures and pressures.
- After being formed, pink diamonds are usually brought to the Earth’s surface through violent volcanic eruptions through kimberlite pipes, where they are eventually mined. However, in the case of the Argyle mine it is the only economically viable pipe in the world made from lamproite.
- 90% of the world’s precious, valuable pink diamonds are from the Argyle Mine in Western Australia. While the remaining 10% are from several places across the globe, including South Africa, Siberia, Tanzania, Russia, Brazil, and Canada.
The Mystery Behind How Pink Diamonds Are Formed: 9 Revelations of Science
New research, published this year in the Science Advances, suggests that diamonds are minute ‘time capsules’ of the sediments that for a time lingered in ancient oceans. These sediments get dragged down deep inside the earth (thanks to the constant recycling of our planet’s surface, known as subduction zones).
While most other fancy colour diamonds already have scientific literature explaining their origin and cause of colouration, the source of the pink hue largely remains a mystery. Scientists studying how pink diamonds are formed continuously work to discover the secret to their pink colour. For instance, blue diamonds get their colour from traces of the element, boron, while yellow diamonds have shown to contain nitrogen. Other diamonds still, get their hue from a range of chemical impurities that absorb light. But for the pink diamonds, no contaminants have yet been found. Leading scientists believe that the colour might be the result of a form of seismic shock that has altered the gemstone’s molecular structure.
According to Post, “Diamonds are the Earth’s messengers. They come from hundreds of miles below the surface, telling us of a part of the Earth that we can’t visit.” Apart from this, these rare stones are also “giving us a peek back in time because they have been formed 2-3 billion years ago.”
“Each one is a time capsule – and the pink diamonds, because they are different from all the other diamonds, have a different story to tell,” adds Post. At present, Scientists have already examined the Australian certified diamonds in Australia, using a mass spectrometer, to find for any impurities that may be responsible for the pink colour. A machine agitates the pink diamonds and analyses the structure of the atoms that are released chemically.
To date, no trace element has been associated with the pink colour of diamonds. Moreover, spectroscopic measurements don’t show any additional features that can ascribe to a particular colouring agent.
Another scientific theory is that diamonds owe their colour to a combination of intense heat and pressure. While still buried deep within the Earth’s mantle, these factors cause distortions in the crystal lattice that absorbs light, which results in their pink hue. The intensely coloured pink diamonds which can almost appear red, share the same colour origin and story on how they are formed.
Diamonds typically form between around 150 and 200 kilometres below the Earth’s surface, crystallising in what are known as cratonic roots – regions of the old, stiff mantle that prop up overlying the continents. To date, the deepest anyone has drilled into the crust is just over 12 kilometres, so no one has been able to study what happens at these extreme depths directly.
Karen Smit from the Gemological Institute of America, states that there is still plenty to learn about how pink diamonds form. “This is happening in inaccessible parts of the Earth, and there are still many unknowns out there.” Smit, a diamond geologist, emphasises that not all diamonds form the same way. Some diamonds grow in the super-deep, at hundreds of miles below the Earth’s surface, while others began their formation in ancient oceans. However, the exact conditions that lead to their formation largely remains a mystery for many scientists.
Scientists have found an astonishing quantity of sparkly diamonds using seismic waves rippling through the Earth to estimate the composition of a particular layer. Their results, published in the journal of Geochemistry, Geophysics, Geosystems, show that the earth may be packed with a thousand times more diamonds than researchers have previously thought.
Check out this less than 3-minute video from BBC News that sets out what we know about how pink diamonds are formed and how they get their pink colour. Click here.
How Pink Diamonds Are Made: The Take-Away
Diamonds are formed deep inside the mantle of the earth, under extreme conditions which require a specific range of pressure and temperature. The rough diamonds, after being formed, are brought to the Earth’s surface by rare volcanic eruptions via the kimberlite pipes where they are typically mined. Hence, the natural pink diamonds in nature are very scarce. This is the reason why pink diamonds commonly command astronomical rates.
On the other hand, some pink diamonds are made by synthesising diamonds in laboratories through processes like chemical vapour deposition (CVD) and high pressure, high-temperature (HPHT) processes.
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