When speaking of diamond quality, we recognise 4 major factors: cut, clarity, carat and colour. Clarity denotes certain inclusions within the gem which got locked in there during the formative stages. These inclusions are the most important factor during research. Colour, on the other hand, is achieved by the diamonds chemical makeup being penetrated by different types of chemicals or changes in their crystal structure. Blue diamonds contain boron, purple diamonds contain hydrogen and green diamonds colour through radiation. It has been noted that exceptional gems contain far less nitrogen than other diamond types, almost always resulting in a type II diamond.
The inclusions in these diamond-types have taught us that the Earth’s core is surrounded by molten metals such as iron and nickel, with limited oxygen. Furthermore, they revealed to have formed between 360 and 750-kilometre depths, far deeper than the 150 to 200-kilometre depths where most other diamonds take shape.