November Editorial      

Diamonds are forever – and more abundant than you might have thought

There are a lot more diamonds in the earth than scientists previously imagined. However, that does not mean that the price of engagement rings or prestige jewellery is going to drop through the floor any time soon. Most the the diamonds revealed by this new scientific study are both microscopic and inaccessibly deep within the earth. So while the abundance of diamonds might not help cash-strapped lovers, they might reveal a lot to scientists studying the oxidation of deep rocks and what happens to fluids moving through them.

Until now it was believed that the chemical reduction of carbon dioxide (a so-called 'redox' reaction) caused an ion change in which the carbon structure was changed to that of a diamond. Likewise the oxidation of methane can cause diamonds to form in a moving fluid, assuming that heat and pressure conditions are favourable.

However, in an article published this month (November 2015) in collaboration with doctoral student Fang Huang, Johns Hopkins University geochemist Dimitri A. Sverjensky postulates a simpler model by which diamonds form as water becomes more acidic as it moves from one rock formation to another. Given the number of different geological formations in which this water movement can take place, some scientists have speculated that this might mean that the deep earth is likely to be 'filled with diamonds'.

The reason that this news will not crash the diamond market is that though the new process is simpler and allows for the creation of diamonds in many different environments, these environments have as common factors intense heat and pressure. The sort of conditions, in fact, which one encounters between 90 and 120 miles (144- 193km) below the earth's surface. By way of comparison, the world's deepest mine of any sort is the Tautona gold mine in Carletonville South Africa, which is 2.5 miles (3.9km) deep.

Furthermore, even if it were possible to dig or drill down to this depth, the abundance of diamonds would be unlikely to impress any would-be fiancée. The process by which it is suggested that these diamonds are formed means that any ring would have to come with its own microscope, as the diamonds would be measured in microns (millionths of a meter) rather than by carats.

Larger, jewellery-class diamonds, are formed when fast-moving volcanic eruptions bring kimberlite pipes to the surface at speeds of 20-30 miles per hour. Because the volcanic mass cools rapidly on reaching the relatively cold surface of the earth, carbon atoms which have formed crystal latitces in the kimberlite are locked into place without the heat energy remaining for them to degrade into graphite.

Overall then, the importance of this new discovery is not so much about the billions of microscopic diamonds beneath our feet, but the new insights it brings into the slow movement of the carbon cycle between the deep and shallow parts of the earth.