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Diamond Buying Guide

When buying a diamond it is important to do your research before you fork out a large chunk of your paycheck. This is because some retailers may make it seem as if you are purchasing a luxury diamond for a fraction of the price, when in fact buying a diamond lower in price means inferior in quality. Using this guide, you will be taught the skills to ensure that you are purchasing a diamond according to your own standards, so you are fully consenting to the quality you are purchasing and are under no illusions.

Imagine you are in a shop and the jeweller hands you a beautiful engagement ring. To determine its quality and worth you begin with the 4 C’s: Clarity, Cut, Colour and Carat weight. These are the traditional units of measure when looking at this precious stone, however, you must add one more imperative ‘C’ to the list and that is Certification.


This relates to the marks of non-crystallised carbon called ‘inclusions’ found within the diamond. The inclusions vary in standards on the spectrum ranging from FL (flawless), SI1 () to I3. It is exceedingly rare for a diamond to be flawless, known as FL and is the highest level on the spectrum. SI1 is in the middle of the spectrum and it is recommended when buying a diamond, you should not purchase lower than this standard. I3 is the lowest as it includes the mot inclusions and is least clear.

Diamond Clarity
Diamond Cut


The cut of a stone is not relating to the shape, but refers to the way the cutter has formed it to best ensure that light bounces within the stone and back out through the top. If it has a defective cut (too long or too short) the light refracts on the inside and falls out down the bottom. This decreases the brightness and lustre of the stone. A well cut stone is neither exceedingly long nor shallow, it is luminous and will always dazzle even when dirty.The grading system varies from Ideal Cut to Good and lastly, Poor Cut. With round diamonds, it is suggested to never purchase below ‘Very Good’ and ‘Good’ in all other shapes. Again, the better cut stone the more it will cost.


Diamonds come in every colour, however, coloured stones are less desired as it diminishes the light's ability to dazzle as it does in colourless diamonds despite the cut. Unless, they are ‘Fancies’ which are rare diamond so unusually strong colour. The grade used to determine the desirability of colour in a diamond is measured from D (colourless) to Z (coloured yellow). The clear diamonds are the most prized and are the most expensive. It is recommended while purchasing a diamond you do not choose one less than grade H.

Diamond Colour
Diamond Carat Weight

Carat Weight

The method of measuring the carat of a diamond is by weight. One carat is 0.2 grams and can be further divided into 100 points which is used to determine the lower carat stones. For instance, a stone with 25 points is 0.25 carats. For a more visual indication of what this means, is the smaller the stone the lower in carat weight and the larger the stone, the higher the carat and price.


Ensure that you receive a certificate when buying diamonds. There are a few highly reputable grading houses around the world and they include GIA, AGS and DCLA. Never accept the certificate of the retailer, even if they are GIA certified. Only accept certificates from the above mentioned graders as they maintain high standards and ensure that the quality of the stone is exactly what you have paid for. Other labs are pressured to lower their standards, therefore you will be paying for a lower quality stone for a higher price.

Diamond Carat Weight

However, if this is not enough, you can go beyond the highest level of quality and purchase a ‘hearts and arrows’ diamond. This is the perfect diamond. It is the perfect cut which enhances the way the light bounces in and out of the top of the diamond. When looking through the telescope from the top you will see arrowheads lining up with the shaft and when looking down on the bottom you will find perfectly shaped hearts. There are many who boast of having the perfectly cut diamond, however though there may be the appearance of hearts and arrows, they can be misleading.

Tips to identify the perfect hearts and arrows:

  • There must be 8 hearts and 8 arrows.
  • All hearts and arrows must be the same in intensity. Meaning one cannot be brighter than the other.
  • All hearts and arrows must be of the same colour.
  • There should be a gap between the heart and V shape under it.
  • The V shape under the heart's must all look exactly the same.
  • Arrow heads and hearts should be the same shape as each other.
  • The arrow heads should line up to the shafts.
  • The hearts should not be pointed.

Be aware that GIA’s highest standard of diamond does not automatically constitute your stone being hearts and arrows. It may state on the card that it is hearts and arrows, however only certificates from HRD Antwerp Labs will provide the guarantee that your diamond is in fact true hearts and arrows.

At minimum it is suggested that you adhere to the 4 C’s and modify your standards according to your budget. Always ask questions to your jeweller, in order to ensure that you are getting what you pay for.