Our Diamond Guide

Our guide to buying the right diamond for you

This page will give a very brief overview of how Jewellers' assess the quality of Diamonds.  No two Diamonds are the same in every way, each as unique and individual as you are.  This page may seem at first like too much technical information but with our expert guidance you will be fully trained up in no time !


There are quality factors that affect the value of Diamonds each one needs to be regarded in collaboration with the other. These factors are commonly known as the four 'C's' and they are Carat, Cut, Colour and Clarity.

The carat weight of a Diamond is essentially the size of the stone.  A carat is 0.2 grams in weight terms. Diamonds weighing less than one carat are denoted in points from 0.001cts to  1.00ct. The size of an individual Diamond refers to the spread of the stone or how many millimeters in diameter.  A simple chart showing the ideal spread of a round brilliant cut stone is shown below.  This should give an idea of how the size of a Diamond may be according to its carat weight.

The Cut of a Diamond is a little more involved than simply the overall shape of the stone. There are many variants in the cutting of a Diamond and this can have a major impact upon the Diamonds beauty, fire, scintillation and invariably its value.  A well cut, well proportioned and well polished Diamond will have such a brilliance and beauty in comparison to a stone of average cut. The shape of a stone or its cut style, could be a square (Princess cut) an oval, heart, marquise (boat shape) rectangular and round and there are many others besides.

The Colour of a Diamond is essentially the lack of colour. There is a colour grading scale starting at D for totally colourless Diamonds through to Z for showing light colours. The highest on the scale, D, is highly prized, relatively rare and of the highest value. There are also coloured Diamonds in hues of yellow, blue, green and red and are graded as to their intensity and saturation throughout the stone.

The Clarity of a Diamond is the amount of natures own hallmarks that are evident in a stone. There are a few features or 'Inclusions' that can be present inside or outside of the cut Diamond. There may be small black marks or featherings, little cracks and fissures evident within the stone itself. The clarity of a Diamond is how free from inclusions the Diamond is. The inclusions can have an impact upon the fire, sparkle and beauty of the stone and can therefore affect the Diamonds value.

Phew !! We know this can be a bit much to take in, but don't worry, we're here to help.

As there are so many variables when selecting your Diamond, choosing the right one can be a daunting prospect.  It is only right that when selecting the right stone you have a trained Jeweller to help you.  At Crown Jewellers we would recommend that you have a selection of un-mounted stones to see first before you purchase.  It's amazing, so many customers tell us instantly when they see Diamonds arranged in front of them that one stands out above the others, almost like the stone is saying 'buy me'. 

Here at Crown Jewellers we have the most amazing Diamond supply chain from legendary sources in Hatton Garden, London.  Our suppliers strictly adhere to the Kimberley process, a guarantee within the Diamond supply chain to be conflict free.  We can supply GIA certificated Diamonds, your guarantee of the quality and grade of your Diamond and the industry's highest regarded.

We have a team of Gemmologists who can help you to choose your Diamond and guide you through your decision process.  Our own on-site first class Goldsmith who will help you to create your own special design. 

You may have gathered by now that purchasing a Diamond isn't just a selection of clicks on your computer.  To really get the best you can, you have to see the Diamonds, get to know them, let them speak to you, have full blown conversations with them, we don't mind.  Please just get it right, first time and come and talk to the team at Crown Jewellers.