The 4 C’s

Diamonds are graded by four characteristics known as the 4 C’s



Diamond and most other gem weights are expressed in metric carats. One carat equals 0.2g or 1/5 of a gram and is divided into 100 equal units called points.


Diamonds are found in a variety of tints and are graded according to their inner body hue on a colour scale that ranges from D being completely colourless through to Z which is strong yellow.

If a diamond’s colour differs from the D to Z colour range, then it is known as a Fancy Colour which is graded according to its intensity. Grading fancy coloured diamonds is complex and specialized, and done by highly trained laboratory graders.

The rarest and most valuable fancy colours are saturated pinks, blues, and greens. Fancy yellows, sometimes referred to as “canary”, and browns, which are known as either ‘cognac” or “champagne”, are more readily available as are black diamonds.

Fancy colours can be enhanced by irradiation and heat treatment. This treatment needs to be declared and the diamond is then referred to as a ‘treated colour’ or ‘enhanced colour’ diamond.


Almost all natural diamonds contain identifying characteristics, known as inclusions. Many of these blemishes are not visible to the unaided eye, yet they are unique to the stone and form the diamond’s own fingerprint, making your diamond truly individual.


As the only characteristic that is governed by the hand of a skilled craftsman, the true beauty of a diamond depends on the way that its cut allows it to reflect and refract light. A well-cut diamond, regardless of its shape, colour and clarity, scintillates with fire and light – unleashing brilliance and beauty!

Diamond Jewellery

Diamond engagement rings or diamond wedding rings use polished diamonds that are set into precious metals. When a diamond is found in its natural state, it is referred to as a ‘rough’ diamond. Once faceted as a cut diamond, whether to be set in diamond jewellery or sold loose, it can be certified and graded according to the four characteristics namely carat, colour, clarity and cut. Diamonds can also be sold uncertified which is often the case with smaller sizes.

Petra has many years of experience working with diamonds. Diamond engagement rings and diamond-set wedding rings are some of our most popular jewellery items for design and manufacture. Our clients are able to choose from a range of stones to suit their individual requirements and preferences and our diamond jewellery is always issued with a detailed valuation certificate. Petra will source diamonds upon request and is available for consultation and advice regarding diamonds and other precious stones.