Nature being what it is , diamonds may show peculiarities of crystallization , which could be minute traces of other minerals trapped during the crystallization process. These may show up as tiny black or white marks.
These natural characteristics are called “inclusions” – nature’s fingerprints.
The number, size and position of any inclusions determines the clarity of a diamond. The fewer the inclusions the rarer it will be, so making it more valuable. Since it is very rare to find a diamond that’s flawless, the closer to flawless the greater the value.
As with colour. There are internationally agreed and accepted standards of clarity.
Most diamonds look colourless, but there are many subtle shade differences and the closer a diamond is to having no colour the more valuable it becomes.
Why does the colour vary? Well, in the chaos of extreme temperature and pressure that first created the diamonds, traces of other elements became mixed with the pure carbon – which is hardly surprising.
It is these traces that give a diamond its colour – or lack of it. Diamonds with no trace of colour are very rare.
But also are rare are diamonds with a strong pure colour. These are called Fancies and are extremely rare. Pink and blue are the most prized, but virtually any colour is possible.
Most gem quality diamonds, seen on their own, do in fact appear to be colourless. But usually they do have at least a hint of colour – this is normally yellow, due to traces of nitrogen.
The only real way of determining the exact colour of a diamond is to place it next to another diamond which has previously been graded.
International standards have been established for grading diamonds according to extremely subtle differences in colour. The main scales are those of the G.I.A (Gemmological Institute of America), Of I.D.L (International Diamond Committee) and of C.I.B.J.O (International Confederation of Jewellery, Silverware, Diamonds, Pearls and stone).