A guide to buying your first diamond ‐ the 4Cs

A guide to buying your first diamond ‐ the 4Cs

The 4Cs are the definitive, globally recognised standard for grading diamonds according to four criteria. If you are buying a diamond, particularly a solitaire diamond for an engagement ring, it is important to know what they mean and how they affect the value of a diamond.

Before they were introduced in the 1940s by the Gemological Institute of America (GIA), there was no universal method of assessing a diamond's quality. Today, they are a vital tool for assessing and comparing diamonds, particularly if you're not an expert.

If your diamond is sold with a GIA certificate you will have a permanent record of the characteristics that make your stone so special, graded by Colour, Clarity, Cut and Carat. All Budrevich engagement rings are sold with an accompanying GIA certificate.

Below, we explain what the 4Cs are and how each plays an important part in the overall beauty of a diamond.


The first C of diamond grading is colour, which is somewhat misleading because white diamonds are actually evaluated based on their absence of colour, on a scale of D to Z. D colour diamonds, which are rare and very valuable, are completely colourless while Z colour diamonds have a visible light yellow or brown hue.

The transition from one colour to the next is incredible subtle ‐ so much so that, unless you are an industry expert, it is virtually impossible to tell the difference. These minute colour distinctions make a big difference to the value of a diamond, however, and play a factor in the decision-making process when it comes to choosing the diamond for your engagement ring.

diamond color chart budrevich hatton london studio

On the GIA Colour Grade scale, which is the industry standard for determining a diamond's colour, D-F colour diamonds are described as colourless, while G-J colour diamonds are considered near-colourless. Exceptionally transparent, D-F colour diamonds are the gold standard for engagement rings, with a barely discernible difference between them. G and H colour diamonds also make excellent centre stones for an engagement ring, with the colour impurities very difficult to detect, particularly with the human eye.


Shaped by nature over millions of years, the vast majority of diamonds contain miniscule flaws, each of which gives a diamond its unique personality. The clarity of a diamond is graded according to the size and number of these imperfections. Those that appear on the outside of a diamond are referred to as blemishes, while on the inside they are called inclusions, which may appear as pinpoints, faint clouds, tiny feather patterns or internal graining.

The majority of these imperfections are completely invisible to the naked eye and can only be seen when the diamond is viewed using a loupe ‐ a small magnifying glass used by jewellers. The smaller the blemish, the less likely it is to interfere with light passing through the stone, which is what causes a diamond to scintillate.

diamond clarity chart budrevich hatton london studio

Just as with colour, a diamond's clarity is graded on a scale, with almost imperceptible differences between each. At the top of the scale are Flawless diamonds, which are rare and extremely valuable, after which comes VVS (Very Very Slight Inclusions), VS (Very Slight), SI (Slight Inclusions) and I (Included).

To further complicate matters, there are two gradings within each sub-category ‐ alongside Flawless there are Internally Flawless diamonds, and VVS diamonds, for example, are graded as either VVS-1 or VVS-2, with minute differences in quality between each.


The cut is one of the most important factors in determining how well the stone scintillates. If it is cut too shallow or too deep, it will compromise the brilliance and fire that brings a diamond to life. Conversely, a well-cut diamond will exhibit superior symmetry, proportion and polish, and sparkle much more intensely.

Round brilliant diamonds are the only diamond shape currently graded for cut by the GIA, using seven distinct criteria. Brightness, fire and scintillation are assessed based on the stone's appearance, whereas weight ratio, durability, polish and symmetry can be attributed to the diamond cutter's skill and artistry.

diamond cut chart budrevich hatton london studio

At Budrevich we only source diamonds that display an excellent or very good cut. In fact, the cut of a diamond is so important that we always encourage clients to prioritise a great cut over a higher colour grade.


Carats have been used throughout history to determine the weight of diamonds and gemstones, with each carat equivalent to 200 milligrams, or 0.20 grams. The term carat is believed to derive from the carob tree, the seeds of which each weigh approximately 0.20 grams. To determine the approximate weight of a diamond, ancient jewellers would use carob seeds placed on balance scales, and while this archaic method has been replaced with high-precision electronic weighing machines, the terminology has endured.

Carat size is often one of the most, if not the most important factor when choosing an engagement ring, with many clients already having a good idea of the approximate weight they are looking for. What they might not know, however, is that the value of diamond increases exponentially. For example, a 1 carat diamond could be three or four times more expensive than a 0.50 carat diamond with exactly the same cut, colour and clarity grades. This is because 0.50 carat diamonds occur more frequently in nature than 1 carat diamonds. Or, to put it another way, the discovery of a 1 carat stone at a diamond mine is a much rarer occurrence than a stone half its size.

The carat weight of a diamond is precisely measured to the hundredth decimal place (for example 0.75 carats), with diamonds weighing under 1 carat often described in points rather than carats. Each point is equivalent to 1/100th of a carat, so a 0.50 carat stone can also be referred to as a 50 point diamond.

diamond carat chart budrevich hatton london studio

If you are looking for a 1 carat diamond, it pays to be flexible. It is impossible to discern the difference between a 0.95 carat diamond and a 1 carat diamond without using digital scales, and with the value of a diamond increasing dramatically from 1 carat upwards, this is a clever way to optimise your budget.

An engagement ring is the most personal of jewels and buying your first diamond the most special of occasions. We invite you to discover a selection of beautiful diamonds and engagement ring designs at our Hatton Garden workshop.