What are the 4Cs of diamond quality? Up until the last century, there was no universally-accepted system for evaluating and grading diamonds. The Gemological Institute of America created the standards that the jewellery industry now uses to judge all diamonds: the 4 Cs – Colour, Clarity, Cut and Carat Weight.

In our 4-part series we dive into each of these different aspects of diamonds and give you tips on how to find great value when purchasing a loose diamond or diamond jewellery.

The cost of a diamond varies greatly and depends on many different factors. Decide which ones are more important for you – is it size, colour, sparkle? Each stone is as unique as a snowflake, and you have a huge variety of different options to find the perfect diamond for you.

Diamond Colour

As colour grade decreases, a diamond typically becomes more yellowish in hue.

The highest colour quality diamonds are best set in white gold and platinum to accentuate the rare lack of colour. Diamonds with colour grades that fall below F can be set into warmer colour metals like yellow gold and will still look great.

Diamonds are graded for colour (from a high of D to a low of Z) and ranked into the following classifications:

Colourless (D-F)
Near Colourless (G-J)
Faint Colour (K-M)
Very Light Colour (N-R)
Light Colour (S-Z)

GIA Diamond Colour Scale

Past the S-Z range, the yellow colour of these diamonds actually starts to become more attractive and valuable. At a certain point they become yellow ‘Fancy Coloured’ diamonds.

Diamond Clarity

Similar to how diamond colour is a measure of the absence of colour, diamond clarity is a rating of the absence of inclusions and blemishes in a diamond. Inclusions are imperfections or flaws inside the diamond, while blemishes are on the surface.

The rating scale for diamond clarity is split up into six categories. These are, in order:

Flawless (FL)
Internally Flawless (IF)
Very, Very Slightly Included (VVS1 and VVS2)
Very Slightly Included (VS1 and VS2)
Slightly Included (SI1 and SI2)
Included (I1, I2, and I3)

GIA Diamond Clarity Chart - The Bench Jewellery Co

Diamond Cut

The rating scale for diamond cut is split up into 5 grades, from excellent to poor. Keep in mind that cut is different than shape. Cut is about how a diamond reflects light.

A perfectly cut diamond crafted by a master diamond cutter will sparkle like no other, and that’s what the rating scale for diamond cut is all about. Since the cut is key to a brilliant and sparkly diamond, it is possibly the most important of the 4Cs of diamond quality and has the biggest impact on its beauty.

Cut is complicated to grade, but it has a huge impact on the value of the diamond. When evaluating cut, diamond graders are looking for:

Brightness – The brightness created by internal and external white light reflecting through a diamond

Fire – The flashes of different colours throughout the stone (like a rainbow)

Scintillation – The amount of sparkle a diamond gives off, and the light & dark areas caused by reflections when the diamond is being moved

The better the cut, the more valuable it is.

Diamond Cut Rating Scale - The Bench Jewellery Co

Diamond Carat Weight

The last ‘c’ of the 4Cs of diamond quality is carat. The standard unit for selling diamonds is by carat (or ‘ct’). Most people generally refer to a carat as a measurement of size, but it’s actually its weight! One carat is 0.2 grams.

Commonly you’ll hear about quarter-carat, half-carat, one carat, two carat diamonds – these are popular sizes. In between those, you get into carat weights with decimal places, like a .67ct stone. A ’10-point’ or ’10-pointer’ is a .10ct diamond, so weighing one tenth of a carat.

Carat Weight - The Bench Jewellery Co.

How Do I Get The Best Value for a Diamond?

Focus on stones in the G-J colour range. To the naked eye (and depending on the metal the diamond is set in), these diamonds will look just like higher colour grade diamonds once they’re set in jewellery.

As we mentioned before, colour is easier to see in larger diamonds, so go for G-H grades for stones 1 carat and up. For those under 1 carat, try I-J diamonds.

When comparing VS1 and SI2 diamonds with the naked eye, you might not be able to notice any difference (and typically only a skilled diamond grader can). Despite this, these diamonds will have very different prices based on their clarity grades.

The majority of diamonds that are sold fall into the Very Slightly Included (VS1-VS2) range. They cost less, but unless you’re looking at them with a microscope you won’t notice any difference compared to the higher grade diamonds.

If you’re more worried about the colour or cut of a diamond, look at stones with SI1-SI2 grades. Those whose primary concern is size (at good prices) may opt for I1 grade diamonds. There will be visible inclusions, but you will get great value.

Since cut is so important to the beauty of a diamond, getting stones with Excellent and Very Good cuts will allow you to opt for lower grades in the other aspects of the 4Cs of diamond quality. With these high-quality cuts, you can get better value by getting diamonds with G-H colours and SI1-SI2 clarity grades without sacrificing all that much in overall appearance.

Even if carat size and/or price are the most important aspects to you, avoid diamonds with Poor grade cuts. These diamonds will appear dull, even with extremely high grades in clarity and colour.

Stick to sizes just under popular ranges (half carat, 1 carat, etc). You may be able to find great value with a 0.94 carat stone, and you’ll barely be able to notice the difference between it and a 1.00 carat.

The 4Cs of Diamond Quality – In Depth

Read more about each of the 4Cs of diamond quality:

The 4Cs of Diamond Quality - The Bench Jewellery Co

The 4Cs of Diamond Quality - Clarity
Diamond Cut Grading - The Bench Jewellery Co
Diamond Carat Weight The Bench Jewellery Co

Learn more about jewellery in our Education section, or contact us and our team of goldsmiths will be happy to answer any questions you may have. We’re here to help!