The 4Cs of Diamonds
The 4Cs of Diamonds
Cut, Color, Clarity and Carat — the four things that decide how a diamond looks and what it costs. Here is how to use them to choose well.
What Are the 4Cs?
The 4Cs are the worldwide standard for describing a diamond. They were introduced by the Gemological Institute of America (GIA) in the mid-20th century and are now used by every major grading lab, including IGI, which certifies our lab grown diamonds. Lab grown and mined diamonds are graded on exactly the same scales.
Cut — The Sparkle Factor
Cut is about how well a diamond's facets are angled and proportioned, not its shape. A well-cut diamond bounces light back to your eye as bright white sparkle (brilliance), flashes of rainbow colour (fire) and lively twinkle as it moves (scintillation). A poorly cut stone leaks light and can look dull, even if its colour and clarity are excellent.
Color — The Less, the Better
White diamonds are graded from D (completely colourless) to Z (noticeable yellow or brown tint). The differences between neighbouring grades are tiny and usually only visible side by side under lab lighting.
Clarity — Nature's (or the Lab's) Fingerprint
Almost every diamond has tiny internal features (inclusions) or surface marks (blemishes). Clarity grades how many there are, how big they are and where they sit, judged under 10x magnification.
Carat — Weight, Not Size
Carat measures weight: one carat is 0.2 grams, divided into 100 "points" (so 0.50 ct = 50 points). Two diamonds of the same carat can look different in size depending on their shape and cut — elongated shapes like Oval, Pear and Marquise look larger face-up than a Round of the same weight.
| Carat | Approx. Round diameter | Good to know |
|---|---|---|
| 0.50 ct | ≈ 5.1 mm | Delicate, everyday elegance |
| 1.00 ct | ≈ 6.4 mm | The classic engagement size |
| 1.50 ct | ≈ 7.4 mm | Noticeably bolder presence |
| 2.00 ct | ≈ 8.1 mm | Statement size |
| 3.00 ct | ≈ 9.3 mm | Show-stopper |
Which C Matters Most?
- Cut — drives sparkle more than anything else.
- Carat — choose the size that feels right on the hand.
- Color — near-colorless (G–H) is the sweet spot.
- Clarity — eye-clean is all you need.
Frequently Asked Questions
Which of the 4Cs is most important?
What colour grade gives the best value?
What clarity should I choose?
Does a bigger carat always look bigger?
Are lab grown diamonds graded the same way?
Do the 4Cs apply to moissanite?
Ready to Find Your Ring?
Explore IGI-certified lab grown diamonds and brilliant moissanite, handmade to order in 925 silver, 10K/14K/18K solid gold or 950 platinum.