A diamond’s quality is assessed using the four Cs – carat weight, cut, colour and clarity. These criteria help you understand a stone’s appearance, rarity and value and provide a common language for comparing diamonds.
### What are the Four Cs?
- Carat weight: Carat measures the weight of a diamond (1 carat = 0.2 grams). Larger diamonds are rarer and cost more.
- Cut: Cut refers to how well the diamond has been shaped and faceted. A well‑cut stone reflects and refracts light for maximum sparkle.
- Colour: Diamonds are graded on a colour scale from D (colourless) to Z (noticeable yellow or brown). Colourless and near‑colourless diamonds are most coveted.
- Clarity: Clarity grades describe the presence of inclusions or surface blemishes. Grades range from Flawless (no inclusions visible under 10× magnification) to Included (inclusions visible to the naked eye).
### Why do the Four Cs matter?
- They let you balance beauty and budget. Choosing a slightly lower colour or clarity grade can dramatically reduce cost while still yielding a beautiful diamond.
- They help you compare stones across jewellers using a standard grading system.
### Tips for choosing a diamond
- Focus on cut: The cut has the greatest impact on brilliance and can make a diamond look bigger and brighter.
- Balance carat and size: Consider diamonds just under key thresholds (e.g., 0.90 ct instead of 1 ct) for better value.
- Pick the right colour: For white gold or platinum settings, G‑H colour diamonds look white; in yellow gold settings, J‑K diamonds can appear warmer yet still beautiful.
- Aim for eye‑clean clarity: VS2 or SI1 diamonds often look flawless to the naked eye but cost less than higher grades.
### Frequently asked questions
- Which of the Four Cs affects sparkle most? The cut grade has the biggest influence on a diamond’s brilliance and fire.
- Do all diamonds come with a certificate? Reputable jewellers provide certification from independent labs like the GIA or AGS that grade diamonds using the Four Cs.
- Are lab‑grown diamonds graded the same way? Yes. Lab‑grown diamonds are graded using the same criteria and typically cost 30–50 % less than natural stones.
- What is the fifth C? Some jewellers refer to “Confidence” as the fifth C – buying from a trusted retailer ensures your diamond is ethically sourced and properly graded.
Last updated: March 2026