Diamond Buying Guide
The Four C’s
In 1939 De Beers introduced a method of evaluating diamonds called the Four C’s. These are Clarity, Colour, Cut and Carat and have become internationally recognised as providing a basis for comparing one diamond to another and essentially grading diamonds.
Clarity
This is defined by the GIA (Gemalogical Institute of America) as ‘the relative absence of inclusions (and blemishes)’. These inclusions are formed by minerals or fractures during the formation of the diamond within the earth. Diamonds are cut to specific shapes and proportions so as a high proportion of light that enters the diamond is reflected back at the observer. The presence of inclusions disrupts the flow of light in the diamond thus diminishing the light reflected back. These inclusions can also impact on the durability of the diamond. A diamond with no inclusions is termed Flawless and has the potential to be remarkably ‘brilliant’. This flawless clarity (FL) is relatively rare and valuable. The following table shows the clarity categories and examples of the spread and number of inclusions:
You will notice the fact that there are subcategories within each of the clarities. This allows for more accurate grading and clarity with a ‘1’ after it will have less inclusions than with a ‘2’ (or ‘3’ in the last ‘Imperfect’ grade).
Colour
This refers to the amount of bodycolour in a diamond. The colour of diamonds are noted by letters of the alphabet starting from ‘D’ for colourless or no yellow, through to ‘Z’ which is a heavy yellow tint. D to K are the most common colours available on the market where D is the most desirable and valuable. The variation of yellow in a diamond is caused by the amount of nitrogen present when the diamond was formed. The following table shows you the GIA (Gemalogical Institute of America) colour grading scale. All the diamond jewellery shown at the Jewellery Collective would be above ‘I’ (for igloo) colour unless specifically ordered.
Please note that there can be a considerable variation in the colour calibration of monitors and the colour spectrum shown is meant only as an educational guide.
Diamonds are also available in deeper shades of yellow and brown as well as other colours such as pink, blue, green, red etc. These are termed ‘natural fancy coloured diamonds’ and are a great deal rarer than ‘white’ diamonds (all apart from brown). Certain colours can demand astronomically high prices and the reason for the colour is due to the presence of various elements during its creation. The colour of diamonds can also be enhanced by bombarding the diamond with electrons. This is called irradiating and the diamonds are called Treated. There are a wide range of colours available and they are a much more cost effective method of owning a coloured diamond.
Cut
This area has two categories; the ‘shape’ of the diamond, and also its ‘proportions, symmetry and polish’. There are a variety of shapes or ‘cuts’ available in diamond and a selection of these is shown below:
The round is also called the brilliant cut and these have been the most sellable for a number of years. Each cut is designed in a way to refract and reflect the light in a certain way giving each cut its own characteristics. For example the Emerald cut has relatively long and fewer facets giving the diamond a ‘corridor’ effect and a rather understated elegance. To give you some idea of the ingenuity of a cut, the brilliant has a total of 57 facets, each positioned to ‘capture’ and ‘throw’ back as much light as possible.
As previously mentioned, cut also refers to the proportions, symmetry and polish of a diamond. Unlike colour and clarity there is no single measurement to categorise its cut. Instead, a collection of measurements and observations to ascertain the relationship between the diamond’s ‘play of light’, dimensions and finish is used. This can be somewhat overlooked in certain areas of the retail industry even though it has a great effect on the value and beauty of a diamond. Bear in mind that a flawless and colourless diamonds can appear lifeless with a poor cut. The line diagrams shows the path of light through diamonds cut too deep, too shallow and ideal cut respectively. Light can be lost through the base (the pavilion) in the deep and shallow diamond whereas the light is reflected back at the viewer in the ideal cut diamond.
The symmetry of a diamond refers to the alignment, positioning and shape of the facets. Poor symmetry will misdirect the light entering and exiting the diamond and hence affect its brilliance. Polish refers to the smoothness of the facets. The final stage of ‘cutting’ a diamond is polishing the surfaces. If the polishing wheel had a flawed surface ,was running too fast, or was against a direction of polishing, then the surface can be dulled, and could dull the diamonds brilliance.
Carat
Carat (ct) is the unit of weight of a diamond and originates from the seed of the carob tree which has a uniform weight and were used by gem traders to measure the weight of stones in ancient civilisations. The table below shows the relation between carat and spread or diamond diameter.
The divisions in between whole carats are signified using two decimal places. Below one carat, the weight of a diamond can also be quantified in ‘points’ (pt) where for example 0.50carat would mean 50 points.
