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Natural Diamonds
As well as being valued for their captivating beauty and hardness, diamonds have even been thought to possess magical properties – in early India, just to gaze upon a diamond was considered strengthening.
What is a natural diamond?
Thought to have been formed between one and three billion years ago, diamonds are one of the oldest substances known to man.
Diamonds were formed deep within the Earth’s mantle between 140 to 190 kilometres below surface, where the high temperature and pressure conditions resulted in the crystallisation of carbon into diamond. The diamonds were then forced through the Earth’s upper mantle towards surface, too fast for their crystalline structure to degrade to graphite, during rare volcanic eruptions of molten rock. As the volcanoes cooled, the magma hardened into carrot shaped ‘pipes’, known as kimberlites.
Not all diamonds would have survived the ascent, meaning that each and every natural gem diamond is a true miracle of nature.
Natural diamonds are rare, and only getting rarer. Inherent production constraints suggest that supply will struggle to keep pace with demand in the long term.
Diamond Stones
White Natural Diamonds
Pure white diamonds are in fact very rare, with yellowish or brown tints being present in the majority of ‘white diamonds’, albeit so faint in many cases that it is undetectable by the amateur observer.
The hint of yellow that can be noted in many diamonds is caused by the element nitrogen, present within the carbon structure. Diamonds containing nitrogen are classed as Type I, whereas those containing aggregated nitrogen atoms are classified as Type Ia (the most common category of diamonds). Diamonds without any detectable nitrogen atoms are exceptionally rare and are known as Type II, with a sub-division of Type IIa, being the purest.
Coloured Natural Diamonds
Nature produces diamonds in every imaginable colour, with over 300 shades and hues having been identified to date. However, it is estimated that only one in 10,000 diamonds has a ‘fancy colour’. The premium prices commanded by ‘fancy coloured’ diamonds are dependent on their tone, saturation and distribution of colour.
A diamond usually comprises more than 99.7% carbon, but the remaining 0.3 per cent constitutes traces of impurities of other elements during its formation. A diamond’s colour is generally determined by such chemical impurities, but it can also be caused by a distortion of the crystal lattice.
African Minerals Can Help You
On its journey from deep in the Earth’s crust to its exquisite polished form, a diamond travels through many highly skilled hands.