Brereton
Diamond Advice - The 4 Cs
Understanding the 4 C's of Natural Diamonds
At Brereton Jewellers, we have been selecting and selling natural diamonds since 1916. Every diamond we offer has been handpicked by our team, guided by a genuine passion for quality and a deep knowledge of what makes a stone truly exceptional.
Before you begin your search, understanding the 4 C's will give you the confidence to choose wisely. And remember: no two natural diamonds are the same. Each stone is a completely unique creation of the earth, formed over billions of years, which is part of what makes owning one so special.
Cut
Of the four C's, cut is the only one entirely shaped by human skill rather than nature. It refers to the precise positioning of each facet - the flat, polished surfaces - across the stone.
A master cutter will study a piece of rough diamond for hours before making a single mark. When the proportions are right, light enters the stone, bounces from facet to facet, and exits in flashes of white brilliance and spectral colour known as fire. These flashes of brilliance and fire are what give the stone its beauty. The other C's count for very little if they cannot be unlocked by the correct cut.
Cut too shallow, and light leaks out through the sides - the stone may look larger than it is, but it will be flat and lifeless. Cut too deep, and light escapes through the bottom, leaving a dark, dull centre. A well cut diamond of modest size will always outshine a larger stone that has been cut purely to preserve carat weight.
Colour
The colour grading scale for natural diamonds runs from D (completely colourless) to Z (noticeably tinted yellow or brown). The closer to D, the rarer and more valuable the stone.
In practice, the untrained eye will tend to only see colour at grade M and above.
D, E, and F are considered completely colourless. This means the stone will be colourless facing upward and also colourless out of its setting facing downward.
G, H, I, and J are in the Near Colourless range and are also completely colourless face up. It is only out of their setting, face down against a white background, that a trained diamond grader will see a hint of colour.
The grades below this will begin to show colour face up in their settings from grade K upward, becoming more noticeable further up the scale.
Clarity
Diamonds form deep within the earth over millions of years, under extraordinary heat and pressure. In that process, tiny minerals and crystals often become trapped inside the stone - these are called inclusions. The number, size, position, and nature of these inclusions determine a diamond's clarity grade.
The majority of these inclusions can only be seen using ten times magnification. The rarest diamonds are "Internally Flawless", meaning that under ten times magnification a trained diamond grader cannot see any inclusions.
After Internally Flawless come the VVS1 and VVS2 grades. VVS stands for "Very Very Slight" inclusions. These minute inclusions are difficult for a trained diamond grader to see under ten times magnification.
Next are the grades of VS1 and VS2. VS stands for "Very Slight" inclusions. These minor inclusions can only be seen under ten times magnification, but a diamond grader will find them slightly easier to locate.
"Slightly Included", or SI, has two grades - SI1 and SI2. These have noticeable inclusions under magnification and a diamond grader will find them easy to see, but they are generally not visible to the naked eye.
"Included", or I, diamonds have, as a rule of thumb, inclusions that are visible to the naked eye. The I grades range from I1 to I3, with inclusions becoming more obvious - and more of a risk to the durability of the diamond - as you go further up the scale. These inclusions tend to dramatically detract from the brilliance of the diamond.
Carat
Carat is simply a measure of weight. One carat equals 0.200 grams, and each carat is divided into 100 points - so, for example, a 0.75ct diamond can also be described as 75 points.
Diamonds become more and more difficult to find in gem quality the heavier they become, so a diamond twice the weight of another is generally worth significantly more than twice the price.
A correctly proportioned diamond of a certain weight should look a certain size. For example, a 1.00ct stone should measure approximately 6.5mm across. Some diamonds are cut out of proportion in order to retain unnecessary carat weight or make a shallow stone look larger than it actually is. This will detract from the beauty and sparkle of the diamond.
Why This Matters at Brereton's
When you visit us in store, you will have the time and the guidance to see, compare, and understand the stones in front of you.
We source only natural diamonds and we are selective. The stones that make it into our collection are the ones that pass every test - cut, colour, clarity, and carat, as a whole. We look at each stone individually, because a diamond is not a formula. It is a one of a kind object, formed by nature, finished by craft, and chosen by people who care deeply about what they sell.
Make an appointment with our team to see the difference for yourself.
