There are 4 main factors you need to be aware of when purchasing a diamond: the colour, the clarity, the cut and the carat size. These are known as the 4Cs and were created by The Gemmological Institute of America (GIA), an unbiased diamond grading authority to serve as a consistent grading system to be used worldwide.
A note from GIA:
GIA created the 4Cs (Color, Clarity, Cut and Carat Weight) as a universal method for establishing the quality of any diamond, anywhere in the world. The 4Cs means two very important things: diamond quality can be communicated in a universal language, and diamond-buying consumers can know exactly what they are about to purchase.
Read more about GIA and their grading systems here
The first factor: Colour
The below table details the diamond grading colour chart, which starts at D and finishes at Z (before moving into 'fancy coloured' specifications).
D-F are considered colourless and demand a premium for this rareity value, G-J are considered near colourless and appear white to the naked, un-trained eye, K-M have a faint colour, where N-Z are drawing more colour but are also beautiful in their own right. When choosing a colour it's important to have your desired size and budget in mind, if you don't mind a faintly coloured diamond - you may be able to have a larger diamond than you initially anticipated.
The second factor: Clarity
The clarity of a diamond, or any precious stone is important, and there are lots of different variations within the clarity grade which are important to remember. The first variation is whether you choose a diamond that has white or dark inclusions, because this will determine how obvious the marks are to the naked eye. It should also be noted that most people will not be able to see inclusions with their naked eye above SI1. The location, size and shape of the inclusions should also be taken into consideration and this can be found on the diamond's certificate.
The third factor: Cut
Another important factor is the shape of the diamond you choose, have a look over the below shapes to find one which suits you:
The fourth factor: Carat Weight
The below table will help determine the mm dimensions of your diamond, though it is important to note that these are guidelines and you should always check the dimensions of your diamond on the certificate.
Confusingly, the mm measurement to carat weight scale isn't liner. You might think that a 1ct diamond would be half the dimensions of a 2ct diamond however, this isn't true. It's best to think of it in terms of mm first and then work backwards.
For more information or help, please contact our GIA Graduate Gemmologist and diamond expert: danielle@duvalandco.co.uk