Diamonds may not be as rare as believed

Diamonds may be more abundant than what is believed, according to a new research which found that the precious stone may be more common deep inside the Earth.
However, this would not mean that diamond jewellery will get cheaper as the diamonds being considered in the research are too small to be visible to the naked eye, and cannot be easily mined, researchers said.
"Diamond formation in the deep Earth, the very deep Earth, may be a more common process than we thought," said Dimitri A Sverjensky, from Johns Hopkins University in US.
The prevalence of diamonds near the Earth's surface, where they can be mined, depends on relatively rare volcanic magma eruptions that raise them from the depths where they form.

Moreover, the diamonds being considered in these studies are not necessarily the stuff of engagement rings, unless the recipient is equipped with a microscope. Most are only a few microns across and are not visible to the unaided eye.
Using a chemical model, Sverjensky and doctoral student Fang Huang at Johns Hopkins University found that diamonds can form with an increase in acidity during interaction between water and rock.

The common understanding up to now has been that diamonds are formed in the movement of fluid by the oxidation of methane or the chemical reduction of carbon dioxide.
Oxidation results in a higher oxidation state, or a gain of electrons. Reduction means a lower oxidation state, and collectively the two are known as 'redox' reactions.

"It was always hard to explain why the redox reactions took place," said Sverjensky.
The reactions require different types of fluids to be moving through the rocks encountering environments with different oxidation states.
The new research showed that water could produce diamonds as its pH falls naturally - that is, as it becomes more acidic - while moving from one type of rock to another.
The finding is one of many in about the last 25 years that expands scientists' understanding of how pervasive diamonds may be, Sverjensky said.
Nobody has yet put a number on the greater abundance of diamonds, but Sverjensky said scientists are working on that with chemical models.

It is impossible to physically explore the great depths at which diamonds are created - roughly 145 km to 193 km below the Earth's surface at intense pressure and at temperatures about 899 to 1,093 degrees Celsius.
The deepest drilling exploration ever made was about 13 or 14 km below the surface, Sverjensky said.
The study will help shed light on fluid movement in the deep Earth, which helps account for the carbon cycle on which all life on the planet depends.
"Fluids are the key link between the shallow and the deep Earth. That's why it's important," Sverjensky said.

The study was published in the journal Nature Communications.