Did you know… Your diamond really is from the ‘centre of the Earth’?
Well, pretty much! Around 150km down ..at roughly 1000c degrees… Throw in enough pressure to pop your ears ten times over (details below), and hey presto, good old carbon changes into that lovely sparkly thing sitting in your engagement ring!
- Take a few trees and other carbon bearing materials from a few billion years ago
- Allow them to get buried deep under ground over a few millennia…
Leave diamond growth process to do its thing for between 1 billion and 3.3 billion years (25% to 75% of the age of Earth!)
- Down in the Earth’s mantle (that’s the layer that contains the tectonic plates that move and cause earthquakes), exert enough ridiculously high pressure (45 to 60 kilobars) with a high temperature (900c to 1300c degrees) (1) and there you have your diamond!
- Rocks containing these diamonds are flung up to the Earth’s surface by ‘deep-origin’ volcanic eruptions ( that’s three or four times deeper than the usual magma that comes out when a volcano normally erupts and so it is quite rare)…..Yep, kind of romantic to think that your engagement ring’s diamond or the diamond studs you wear all the time came to you through a magnificent natural occurrence!
- The correct combination of temperature and pressure is only found in the thick, ancient, and stable parts of continental plates where regions of lithosphere known as cratons exist. Long residence in the cratonic lithosphere allows diamond crystals to grow larger. (2)
Right, lesson over!
Now have a browse and see which other bits of (naturally amazing) diamond jewellery you need to add to your collection…
(1) Carlson, R.W. (2005). The Mantle and Core. Elsevier. p. 248. ISBN 0-08-044848-8.
(2) Erlich, E.I.; Dan Hausel, W. (2002). Diamond Deposits. Society for Mining, Metallurgy, and Exploration. pp. 74ÔÇô94. ISBN 0-87335-213-0.