The Four Cs

This article has mentions of products from one or more companies, and I may receive compensation if you purchase those products following reading my recommendations.

The Four Cs

This article has mentions of products from one or more companies, and I may receive compensation if you purchase those products following reading my recommendations.

Even the most novice of diamond buyers have likely heard of the four C’s. The simple mnemonic effectively encompasses the most crucial factors when buying a diamond, making it easier to remember the all-important steps towards diamond success.

Aside from cut quality, which is a quality factor that cannot be compromised, the four C’s offer flexibility to buyers, allowing them to prioritize those features which they feel are most important, and find a suitable balance of budget and beauty on those that are less impactful. With such a multitude of combinations in diamond quality, there is truly a diamond out there for everyone, and getting to grips with the Four C’s will empower you to make the best choices on your diamond journey.  


When diamonds are pulled from the earth in their ‘rough’ state, it seems unimaginable that they will be transformed into the bright and brilliant beauties that grace our jewelry. The cut refers to the proportions of the facets and is the aspect of diamond beauty that is controlled by man.

For brilliant cuts, the goal is to create numerous small facets that behave like mirrors, successfully bouncing light into the diamond and back to the eye of the viewer. A good cut will deliver the perfect balance of fire, brilliance and scintillation. A poor cut will result in light leakage and a dull, lacklustre diamond.

For step cuts such as Emerald and Asscher, the aim is not sparkle but instead long, linear facets and wide tables that create an alluring ‘hall of mirrors’ effect that showcases a diamond’s perfect color and clarity. It is for this reason that step cuts require higher clarity and color grades than brilliant cuts.

Though often used interchangeably, diamond cut and diamond shape are two very different things. The shape refers to the outline of the diamond (i.e. heart shape, round shape) whilst the cut is specific to and angles, proportions and facets of the diamond.

The above image shows a sample GIA dossier, including the diamond measurements. You will find lists of ‘ideal’ proportions for diamond cut, with small variance between them, and these can be helpful for narrowing down your search. However, the modern buyer will be pleased to know the technology is here to help. The best diamond vendors will offer advanced diamond imaging and performance reports. ASET, Hearts and Arrows, Idealscope and Sarine technologies can all give you tangible data in a user-friendly format that tells you exactly how the diamond is handling light. If you don’t have a head for numbers and find yourself befuddled by crown angles and pavilions, these images will prove invaluable to your search. Remember; light return = sparkle.

Take a closer look at diamond cut in this guide.


When it comes to the color of a diamond, colorless diamonds, also referred to as white diamonds, are the most popular for engagement rings and other fine jewelry. The presence of nitrogen, which becomes present during the diamond’s formation in the earth, causes the diamond to take on a yellow tone which is undesirable. The scales tip when stones because intensely colored and are classified as ‘fancy colored diamonds’; these brightly colored stones are graded separately to colorless diamonds.

Diamonds within the colorless category (D-F) command the highest prices due to their rarity, yet diamonds in the near colorless bracket (G-I) are usually indecipherable from the higher grades. My complete guide to diamond color will explain how to get the best trade off between a bright white diamond and a reasonable spend.

Complete your diamond color education here.


Clarity refers to the internal (inclusions) and external (blemishes) characteristics of a diamond. Most inclusions occur naturally as a diamond forms in the earth, but some are created during the polishing process or during enhancement. A natural reminder of a diamonds magnificent journey from earth to hand, all diamonds will contain inclusions to some degree, in many cases they can impede light return, diminish sparkle and even compromise the durability of a diamond.

Clarity is one of the more complex areas of diamond quality grading. Diamonds are graded on the amount, size, relief, positioning and type of inclusion or blemish. Highly skilled graders much reach the same conclusion before a grade can be determined.

Despite being an intricate feature of diamond grading, for buyers the rules for selecting a diamond clarity are much more straight forward. Finding a diamond that is eye-clean is the name of the game. Eye-clean diamonds (which have no visible inclusions to the naked eye) can be found at an SI1 grade and above. The higher grades are much rarer and thus more expensive, but providing a diamond is eye-clean and has no inclusions that compromise the structure of a diamond, it is possible to maintain a reasonable spend on diamond clarity.

You can read more about diamond clarity here.


This refers to the weight of the diamond. A standard carat is 200 milligrams, and each carat is subdivided into 100 points. For example, you may see a half carat diamond expressed as 0.50ct or 50 points. Carat is the only factor that can be precisely and objectively measured.

Buyers are, naturally, more concerned with the size of a diamond. While carat weight can tell you a little (a 1 carat diamond is obviously smaller than a 2-carat diamond), it is actually more complex that this. There is no average ‘size’ for a one carat diamond as the cut and diamond shape will also impact how big the diamond appears. This is why choosing a fantastic cut is so important – it will make your diamond look bigger!

Finding a gem quality diamond at the heavier carat weights is much harder, so the price increases not only with the weight but with the rarity and desirability.

Bigger or brighter? Find out which carat weight is best for you in this article.

I have pages explain each of the four Cs in detailed should you wish to find out more - CutColorClarity, and Carat

Make sure you read my detailed review pages as well, I would recommend starting with Whiteflash (best quality), Blue Nile (good selection) and Leibish and Co (great for colored diamonds.)