There is some excitement in Russia concerning the discovery of diamonds from a lava of the Tolbachik volcano in the Kamchatka peninsula near Alaska. These diamonds were formed from pressurised volcanic gases under the influence of electrical discharges of lightning during eruption, this particular case being the 2012-2013 eruption.
But you need to keep matters in perspective because on closer examination these diamonds are ‘micro-diamonds’ ranging in size from 250 to 700 microns in size and identified from electron microscopy and X-ray diffraction; not exactly the size you would put on a ring, or in the argot, bloody smaller than Indian goods. (A micron is one millionth of a metre so describing these diamonds in weight terms, carats, would be futile). De Beers is under no threat.
The article linked above from the Siberian Times uses the usual mainstream plate-tectonics model, not drawn to scale either, and it’s quite simplistic.
The fact is that large gem quality diamonds, think of the Cullinan Diamond from the Premier Mine, are restricted to kimberlites on stable continental cratons. This is the De Beers model which has not yet been falsified, and a rule of thumb was the Hawthorne-Hissink model in that you find kimberlites where you find them, a model that assaulted the sensitivities of most geologists who fervently believe that kimberlites have to be structurally controlled and thus potentially predictable and targetable.
This model is based on the standard diamond stability plot.
Hence the De Beers model was that diamonds are the stable phase at 220 km depth and that ‘somehow’ they were carried up as xenocrysts in a kimberlite magma during a very short travel time, necessary to preserve the diamond in contact with the olivine rich magma during its ascent to the surface. Kimberlite are also known to be super-charged with CO2 during eruption, and the mechanism of diatreme formation described by the Scott-Smith theory, that I have suggested is due to downward machining Birkeland currents.
The Russian report also mentions a French patent for synthetic diamond production using methane (CH4) and high voltage electrical discharges. General Electric and De Beers also manufacture synthetic diamonds and these are cheaper to manufacture than to actually mine them.
One of the puzzles of diamond geology is the occurrence of diamonds away from the stable continental cratons such as the Nullagine diamonds in the West Australian Pilbara and the Copeton diamonds in New South Wales, found in Quaternary alluvial deposits, (or whatever label the geochronological nomenclature body has used for this age period).
The problem is that the Nullagine and Copeton diamonds have not been traced to a primary source rock. Similar mysteries occur elsewhere on the Earth where alluvial diamonds in the SW of South Africa (Annex Kleinzee for example) had an unknown provenance and one suggestion was that these diamonds came from Brazil before South America was separated from Africa. (However it was not a convincing explanation, come to think of it, and a more logical explanation was that these diamonds were derived from perhaps a tributary of the Orange River in the past, or some other palaeodrainage whose catchment was the Kimberley diamond field to the east in South Africa). The belief for the NSW occurrences, is that these were produced by a plate-tectonics subduction process without the necessity of deep sourced magmas such as kimberlite or lamproite.
But what about the Russian discovery? An excellent summary of the 2012-2013 eruption of ‘andesites’ may be studied here.
Plosky Tolbachik eruption showing lightning
Given CH4 and CO2 as gaseous components of the Kamchatka type volcanoes, then coupled with the observed electrical discharges, formation of micro-diamonds becomes quite plausible. However the formation of macro-diamonds, 11 points and above (100 points to a carat) requires a long period of crystallisation and cannot be explained by the short-term eruptive process observed at the Tolbachik eruptions. These had to have formed during the geological past, and then the question arises of whether the carbon they formed from originated at the surface and were plunged into the mantle, or developed in-situ in the mantle in the first instance. The explanation for this then involves the fundamental principles of the origin of life, is it an epiphenomenon of physical reality, the existing paradigm, or is it as Amit Goswami and others suspect, that physical reality is an epiphenomenon of life/consciousness.