Clarity, Colour, Carat Weight, and Cut. These are the four C’s of diamonds you should look out for when you appraise a diamond you’re interested in. We will explore these in some depth so you are well equipped the next time you go shopping and have confidence in your acquisition.
Diamonds are formed under an incredible amount of heat and pressure within the earth. They often contain unique birthmarks, either internal (inclusions) or external (blemishes).
- Inclusions can interfere with the passage of light through the diamond, so the fewer the inclusions, the more brilliant a diamond.
- Blemishes include surface irregularities. They lower the value and luster of a diamond.
A diamond’s clarity rating is based on the inclusions and blemishes that are visible under 10x magnification. Diamonds without these imperfections are rare and, naturally, very valuable.
Diamond grades (clarity rating) range from Flawless (completely free of blemishes and inclusions) to Included 3 (possess large, heavy blemishes and inclusions visible to the naked eye).
The eleven different clarity grades assigned to diamonds
A diamond’s colour has a significant impact on its value & appearance. A diamond is like a prism that divides light into an array of colours. A colourless diamond allows more light to pass through it, emits more sparkle, and is hence more valued than a coloured diamond with the exception of fancy coloured diamonds.
Colour is a result of lingering traces of nitrogen, boron, hydrogen or other elements present in the composition of the diamond. We follow an international grading system that begins with the letter D (colourless) and continues with increasing presence of colour to the letter Z. The distinctions between successive letters are very subtle & tough to observe to the untrained eye.
A summary illustration of colour grading
Fancy coloured diamonds are also available in: black, brown, champagne, cognac, etc. In the case of these diamonds, the intensity and hue of the colour plays the most important role in deciding the value of the stone, not the clarity. A diamond with an intense colour and rare colour (red), can be more expensive than a colourless diamond.
A carat is the unit of measurement used to describe the weight of loose diamonds. One carat weighs 200 grams and, just as a dollar is divided into 100 pennies, a carat is divided into 100 points. As such, a stone weighing 1.50 carats has a weight of 1 carat and 50 points.
Diamonds of the same weight do not necessarily have the same appearance. When diamonds are mined, large gems are discovered much less frequently than small ones, hence making them much more valuable.
As an illustration of how diamond pricing works, consider this example: A 2 carat diamond of F colour, VVS1 clarity will always be worth more than two 1 carat diamonds of the same colour, clarity and cut. In contrast, a smaller 0.50 carat diamond with high colour and clarity ratings may cost more than a 0.75 carat diamond with lower colour and clarity ratings.
Note that as diamond carat size increases, both the diameter and the depth of the diamond increase. This is why a 1 carat diamond (about 6.5 mm in diameter) does not look twice as wide as a 0.50 carat diamond (about 5 mm in diameter).
Diamond sizes in carats and millimetres
A good cut gives a diamond its brilliance.
Cut refers to the proportions of the diamond relative to its shape (round brilliant, marquise, pear, princess, etc.) Every diamond, regardless of its shape, gets its brilliancy and scintillation through its cut and polish, which allow the maximum amount of light to enter through its top, be reflected, and dispersed back through its top.
Rough diamonds, those that are mined from the earth, do not display all their beauty. They need to be cut and polished to exhibit the brilliance that diamonds are known for.
The most popular shape for diamonds is the round Brilliant cut with 58 facets. Stones that are not cut into this shape are known as fancy cuts. The cut of the diamond is often determined by the original shape of the rough stone, the location of the inclusions, the flaws to be eliminated, and the preservation of weight.
The drawing shows the play of light inside a diamond and explains why an ideal cut diamond has the maximum luster.
The 4 C’s of diamonds are the central pillars to learning about diamonds. They provide the foundations upon which we build the more advanced topics and allow you to understand the diamonds you are looking at.