4 ‘C’s of Buying Diamonds

Superior diamonds are born of stringent quality standards. The most important diamond categorising and grading facets are embodied in the 4 Cs. The world’s most valuable diamonds possess the best in all four measurements of:

  • Clarity
  • Colour
  • Carat
  • Cut

Master jewellers use the four Cs to grade diamonds. Learn more on how to use the 4 C's of buying diamonds and how you should too use them to grade your diamonds.



Clarity is a measure of diamonds flawlessness. Almost every diamond incurs blemishes during its natural formation. Only a stone that reveals no external or internal flaws under 10-power magnification can claim this honour. So a truly flawless diamond is extremely rare and highly valuable.

A diamond’s sparkle can disguise almost any imperfection. Some have little or no impact on the diamond’s visual appearance.  Others are visible to the naked eye.  All diamonds receive a clarity rating based on a world industry standard scale:

Internally flawlessVery very slight inclusionsEye clean but slight inclusionsVisible to the naked eye



Be entirely clear about diamond colouring. While diamond colour grade is important to overall quality performance, transparency is often key. Enchanting colour flecks within your diamond are often caused by tiny impurities.

On a precise industry scale from D (colourless) to Z (saturated), qualified gemologists colour grade each diamond. D scaled diamonds are entirely transparent, thoroughly rare and costly. These must not be confused with natural coloured diamonds, which are themselves an exceptional treasure.



Diamond weight is measured in carats. But carat weight alone does not determine your diamond value or size. Never select a diamond on carat alone or in isolation of the other Cs. To enjoy the finest possible diamond beauty and integrity, choose your ideal cut, colour and clarity first.

A lower carat weight diamond of superior cut, clarity and brilliance will always prevail. Similarly don’t let carat weight be your sole measure of diamond size. Consider carat weight alongside:

  • millimetres across your diamond’s top surface
  • your chosen diamond’s cut grade



Ultimate brilliance depends upon diamond cut. A delicate balancing act must be undertaken during diamond cutting. Fashioning a diamond for reflective qualities without sacrificing too much diamond size.

A diamond cutter is charged with shaping, positioning and angling each facet with absolute symmetrical precision. So maximum brightness and light emanates from the diamond's very heart. How dazzlingly your diamond sparkles indicates how skilfully your diamond cutter did their work.