Diamond Education
The 4Cs of Diamonds
Cut, colour, clarity and carat are the four measurements every diamond is graded on. Together they decide how a diamond looks and what it costs. This guide explains each one in plain words, shows the grades side by side, and tells you exactly where Civia's diamonds sit, so you can choose with confidence.
Updated October 2026 · 8 minute read
- Cut
- Sparkle
- Colour
- Whiteness
- Clarity
- Purity
- Carat
- Weight
01The basics
What the 4Cs mean
Every diamond is unique, so the industry grades it on four separate measurements. No single C tells the whole story: a large diamond with a poor cut can look dull, and a perfectly clear diamond with a yellow tint can look warm. The best diamond for you is the one where the four are balanced for your eye and your budget.
Lab-grown diamonds are graded on exactly the same scales, by the same kind of independent laboratories, as mined diamonds.
02Cut
Cut: the C that creates sparkle
Cut is about craftsmanship, not shape. It measures how well a diamond's angles, proportions, symmetry and polish send light back up through the top of the stone. A well-cut diamond throws white light (brilliance), flashes of colour (fire) and sparkle when it moves. A poorly cut one leaks light out of the sides and bottom and looks glassy or dark in the centre.
Because cut has the biggest effect on beauty, it is the C we recommend you never compromise on.
| Grade | What you see |
|---|---|
| Ideal / Excellent | Maximum brilliance and fire. Light returns evenly across the whole stone. |
| Very Good | Bright and lively; the difference from Excellent is hard to see without a side-by-side. |
| Good | Pleasant sparkle, with some light lost through the sides. |
| Fair / Poor | Noticeably duller, with dark or glassy areas. Not used in fine jewellery. |
Cut is not shapeShape is the outline of the diamond (round, oval, pear and so on). Cut is how well that shape has been faceted. Every shape can be cut well or badly. You choose the shape on each Civia product page.
03Colour
Colour: from D to Z
Colour grading is about the absence of colour. The scale starts at D, completely colourless, and runs to Z, which has a light yellow or brown tint. The differences between neighbouring grades are tiny and are judged by experts against master stones under controlled light.
Colourless grades (D, E, F) look icy white in any metal. Near-colourless grades (G to J) still face up white to most eyes, especially in yellow or rose gold, which warms the stone anyway.
Where Civia sitsOur engagement ring centre diamonds are offered in the colourless range: D, E or F, chosen on each product page.
04Clarity
Clarity: how clean the diamond is
Almost every diamond has tiny natural features inside (inclusions) or on the surface (blemishes). Clarity grades how many there are, how large, and how visible, under 10x magnification. Most are far too small to see without a loupe.
The phrase to know is eye-clean: a diamond whose inclusions you cannot see with the naked eye at a normal viewing distance. From VS2 upwards, almost every diamond is eye-clean.
| Grade | Name | What it means |
|---|---|---|
| FL / IF | Flawless / Internally flawless | Nothing visible inside even at 10x. Extremely rare. |
| VVS1 / VVS2 | Very, very slightly included | Inclusions so small a trained grader struggles to find them at 10x. |
| VS1 / VS2 | Very slightly included | Minor inclusions visible only under magnification. Eye-clean. |
| SI1 / SI2 | Slightly included | Inclusions visible at 10x; SI2 can sometimes be seen by eye. |
| I1 – I3 | Included | Inclusions visible to the naked eye; can affect sparkle and durability. |
Where Civia sitsOur centre diamonds are offered in VS1, VVS2 and VVS1 clarity: all eye-clean, chosen on each product page.
05Carat
Carat: weight and size
Carat is a unit of weight, not size: one carat equals 0.2 grams, and it is divided into 100 points (so 0.75 ct is "75 points"). Two diamonds of the same weight can look different in size depending on their shape and cut. Elongated shapes such as oval, pear and marquise look larger from the top than a round of the same weight.
On jewellery with several stones you will see ct tw (carat total weight), the combined weight of all the diamonds in the piece.
| Carat weight | Round diameter (approx.) | On the hand |
|---|---|---|
| 0.50 ct | 5.1 mm | Delicate and understated |
| 1.00 ct | 6.4 mm | The classic engagement size |
| 1.50 ct | 7.3 mm | Noticeably fuller on the finger |
| 2.00 ct | 8.1 mm | A statement centre stone |
| 3.00 ct | 9.3 mm | Bold; covers much of a slim finger |
| 5.00 ct | 11.0 mm | Dramatic red-carpet scale |
Diameters are typical for a well-cut round brilliant; every diamond varies slightly.
Where Civia sitsMany of our engagement rings are offered from 1 to 9 carats. Because lab-grown diamonds cost far less per carat than mined ones, a larger stone is often within reach without lowering the other three Cs.
06Grading
Certification: proof of the 4Cs
A diamond grading report is an independent laboratory's record of a specific diamond: its shape, measurements, cut, colour, clarity and carat weight, plus a unique report number. Lab-grown diamonds are also identified on the report as laboratory-grown.
The best-known laboratories are the IGI (International Gemological Institute), the most widely used for lab-grown diamonds, and the GIA (Gemological Institute of America). You can check any report on the laboratory's website by entering its number.
- The report number is often laser-inscribed on the diamond's girdle, so the stone can be matched to its paper.
- A report describes the diamond; it is not an appraisal of its price.
At CiviaCertification is listed under Specifications on every product page. Ask us before you order and we will confirm the report details for your diamond.
07Our advice
How to balance the 4Cs for your budget
You do not need the top grade in every C. Spend where the eye notices and save where it does not:
- Put cut first.An excellent cut makes a diamond look bigger, brighter and whiter. It is the best value for your money.
- Choose an eye-clean clarity.VS1 or higher looks perfectly clean to the eye; paying for Flawless buys rarity, not visible beauty.
- Match colour to the metal.White gold, platinum and silver show colour most, so D–F suits them. Yellow and rose gold are more forgiving.
- Then decide on size.With cut, colour and clarity set, pick the carat weight that feels right on the hand and in your budget.
- Think about shape.Oval, pear and marquise look larger per carat than round, and hide colour a little more than step cuts like emerald.
08Questions
Questions about the 4Cs
Which of the 4Cs is the most important?
Cut. It has the biggest effect on sparkle and on how large and white a diamond looks. A well-cut diamond with slightly lower colour or clarity usually looks better than a poorly cut one with top grades.
Are lab-grown diamonds graded the same way as mined diamonds?
Yes. They are graded on the same cut, colour, clarity and carat scales by independent laboratories such as IGI and GIA. The report also states that the diamond is laboratory-grown.
What does eye-clean mean?
It means you cannot see any inclusions with the naked eye from a normal viewing distance. VS2 and higher clarity diamonds are almost always eye-clean. All of Civia's centre diamonds are VS1 or higher.
Is a D colour diamond worth it over F?
D, E and F are all colourless, and the difference between them is very hard to see once the diamond is set. D is the rarest and most prized; F gives the same icy look for less. Choose D if you want the very top grade, F if you want the best balance.
Does a higher carat always mean a bigger-looking diamond?
Not always. Carat is weight. A deep, poorly cut diamond hides weight underneath, while a well-cut one spreads it across the top. Shape matters too: an oval looks larger from above than a round of the same weight.
What is the difference between ct and ct tw?
ct (carat) is the weight of a single diamond. ct tw (carat total weight) is the combined weight of every diamond in a piece of jewellery, such as a halo ring or a tennis bracelet.
How can I check a diamond's certificate?
Enter the report number on the laboratory's website (for example igi.org or gia.edu). The online record should match the shape, measurements and grades on your paper report.
Can someone help me choose?
Of course. Our diamond team is happy to compare options with you, send extra photos or videos, and suggest the best balance for your budget. Contact us at support@civiajewels.com or +1 (437) 422-1187.
