Following is some essential background information which we hope will be easily understood and assist you when making a diamond purchase.
All Diamonds are unique and precious. A Diamond is likely to be the oldest item you will ever own – formed within the earth’s crust millions of years ago, the youngest being around 900 million years old! Diamonds are formed at high temperature and pressure and have been forced upwards through volcanic eruptions. The Diamond is the hardest mineral on earth and when well cut and polished has exceptional fire and brilliance. When buying a diamond it is advisable to have an understanding of the ‘4 C’s’; Carat, Cut, Colour and Clarity. The grading of a diamond and interaction of the ‘4’C’s’ has direct influence on the value of a diamond
Carat refers to the diamond weight. One carat is divided into 100 points; a diamond of half-a-carat weight may also be referred to as ‘50 points’ or written as ‘.50ct’. As diamond carat weight increases, both the diameter and the depth increase, explaining why a one carat diamond does not look twice as large as a half-a-carat diamond. Large diamonds are much rarer than small ones, therefore, diamond value increases exponentially for certain thresholds of diamond carat weights where demand is high. eg a one carat diamond will cost more than twice as much as a half-a-carat diamond of comparable quality.
Diamond Carat must not be confused with gold ‘carat’, which refers to the purity of gold.
Of all the 4 C’s, the diamond ‘cut’ is the only feature directly influenced by man. It is, in our opinion, one of the most important aspects of the 4 C’s, yet is often little understood. It fundamentally refers to the ‘angles’ and ‘proportions’ of the cut diamond and secondly to the ‘shape’ of the diamond, but it is essential that these two should not be confused. Diamond cutting is the art, skill and increasingly, the science of transforming a diamond from a lustreless opaque rough crystal to a beautiful brilliant gemstone. A truly well cut, polished and ‘made’ stone is the result of excellent craftsmanship of the diamond cutter who works with absolute precision to release the brilliance, radiance and fire within the diamond.
A well cut proportioned stone, regardless of its shape, allows light in from the top, to be reflected from one facet to another and then back out again at the top, presenting a bright and lively stone. Two diamonds of similar size, clarity and colour may appear identical but when viewed, they are poles apart. The shape of the ‘rough’ often determines the end shape of the cut stone. This can mean that instead of being well proportioned, where much of the rough is lost, the stone is cut for maximum carat weight. It is, therefore, likely that the diamond is poorly cut and proportioned.
It will be either too shallow or too deep and will not have the same intense light reflection, much of the light being lost through the sides instead of reflecting back and out. Badly proportioned diamonds can appear dull and lifeless. We would strongly advise viewing one diamond against another prior to purchase, there is absolutely no substitute. Your purchase is an important one and your diamond must be lively, have brilliance and be attractive and pleasing to the eye.
The skill of diamond ‘cutting’ evolved over the centuries, however it was not until 1919 that Marcel Tolkowsky mathematically calculated the formula for the modern Round Brilliant Cut Diamond. With fifty-eight individually polished facets, the Brilliant Cut Diamond continues to produces the greatest fire, brilliance, dispersion and ‘sparkle’ of all the major shapes. Fancy cut shaped diamonds, ie marquise, pear-shaped, heart, princess-cut, radiant, asscher-cut, oval, emerald-cut are achieved by variations and combinations of the brilliant-cut and the ‘step-cut’ patterning, apart from the emerald-cut which is only ‘step-cut’. Unlike the modern Brilliant Cut Diamond there are no mathematical guide-lines to the optimum cutting of these shapes. The rough will often determine the end result. However it is still important to consider the ‘4 C’s’ – and we would strongly advise that you are guided by an expert in your purchase. The diamond should be ‘pleasing’ to the eye with good symmetry and not carry too much of the weight in the depth. Some Fancy Cut Diamonds may attract a ‘premium’ on the price but this can fluctuate with fashion, supply and demand.
Diamonds are further graded by colour – the more ‘colourless’ the diamond, the more rare it is and the higher the price per carat.
The universal diamond colour scale runs from ‘D’, colourless to ‘Z’ light yellow Diamonds from ‘H’ grade and above are categorised as ‘Fine White’. From ‘K’ down a slight tinge of yellow can be detected, Colour differences between the grades are subtle. It would be difficult for the untrained eye to detect the difference between, say ‘E’ to ‘F’ grade, but a discerning eye may be able to see the colour difference between two or more grades, say ‘E’ to ‘G’. For best value we would recommend grade ‘H’ and above.
Some of the rarest diamonds are categorised as ‘Fancy Coloured Diamonds’ and can range in colours from pink, blue, yellow, green, champagne and cognac. The colour intensity varies from a mere tinge to full depth; the more intense the colour the rarer the diamond.
Clarity refers to the ‘purity’ of the diamond. Almost all diamonds have natural inclusions or birthmarks. They may appear as tiny crystals, clouds or feathers. The clearer the stone, the rarer the diamond and higher the price.
Diamond clarity is graded into eleven grades (below) from Flawless (FL) to Included (I3)
All grades from SI2 and above are known as ‘eye clean’, that is, undetectable to the human eye – inclusions can only be detected under 10x magnification. We recommend you examine diamonds with a jeweller’s ‘loupe’ prior to purchase. Some inclusions can be cleverly hidden by mounting. Depending on your requirement, the clarity SI – Slightly Included, represents best value since the inclusions are not visible to the naked eye and prices are reasonable when compared to prices of VS grade and above
We hope that this information has been helpful. If you are about to purchase a diamond, we would be delighted to take you through the 4 C’s personally. Do contact us with your requirement.
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