Diamond Quality

When buying a diamond, your personal preference or the preference of the person you are buying for is the most important thing to consider. Once that is decided you will want the highest quality for your budget. To help you choose, you can look at the 4C’s – carat weight, colour, clarity and cut. For security ask for diamond certification.

Carat weight

The price of a diamond increases in relation with its carat weight, but not in relation to its actual size. This means that when carat weight triples from 1 to 3 carats, the perceived size more or less triples as well, though in reality the diameter of the diamond increases by only 45 percent.

Two diamonds of the same shape and carat weight can appear different in size, depending on how they have been cut. Different shapes matter too, a one-carat marquise diamond usually appears larger than a one-carat round diamond.

A two-carat diamond with a lower grading for cut, colour, and clarity may cost less than a higher graded one-carat. Also worth noting is that a 0.9 carat diamond will cost a lot less than a one-carat, even though its difficult to distinguish the two.


Diamonds come in a range of colours, some of which are highly prized like pink, canary yellow and blue. In a white diamond, a yellow tint will bring a lower price tag, since if affects the sparkle.

All white diamonds are colour graded and given a letter from D to Z:

Colourless Near Colourless Faint Very Light Light

Since the most important factor in a diamond’s brilliance is its cut, the best value colour would be a G-H for diamonds over one carat and I-J for those diamonds less than one carat. Once the diamond is set, it will look like a higher grade. A lower colour diamond with a higher cut grade will have more sparkle and visual appeal than a higher colour diamond with a lower cut grade. If you want to hide the colour, choose a brilliant cut stone like the princess shape as these have more facets than step cuts such as the emerald or asscher.


Nearly all diamonds have small imperfections either blemishes on the outside, or inclusions on the inside. The grading of clarity relates to how many of these imperfections are visible. The impact of a flaw is how it will interfere with the sparkle of the diamond, though clarity does not have much of an impact on diamonds less than one-carat.

Diamond clarity characteristics are graded and considers number, size, colour, reflectivity, and position of every flaw visible under 10x magnification. The 11 point diamond clarity scale is:

  • Flawless: no inclusions or blemishes.
  • Internally Flawless: no internal inclusions but may have slight surface blemishes.
  • Very, Very Slightly Included (VVS1) and (VVS2): minute inclusions difficult to see, even under magnification.
  • Very Slightly Included (VS1) and (VS2): minor inclusions detected easily under magnification but not by the naked eye.
  • Slightly Included (SI1) and (SI2): noticeable inclusions under magnification that can be visible to an unaided eye.
  • Included (I1), (I2), and (I3): obvious inclusions easily visible to the naked eye with potential durability risk the further down the scale you go.

If you have a diamond less than one-carat an SI1 or SI2 works well. For diamonds over 1 carat go no lower than an SI1. For 2 carats, a clarity grade of VS2 is the better option.

Brilliant-cut diamonds, such as round, princess, oval, cushion, pear and marquise, hide inclusions well. If you want a step-cut, choose a clarity grade one grade higher than for a brilliant cut diamond.


The cut of the diamond provides its brilliance and beauty more than anything else. A well-cut diamond will have more life and sparkle than one with a lesser cut quality. The perfect cut creates three optical effects including brightness, which is the white light reflection off the diamond; fire, which refers to the flashes of colour a diamond displays as light refracts, and scintillation which is the perfect contrast between the light and dark areas of a diamond so it sparkles when it moves.

There is a cut-grading system, which can be slightly different between laboratories. Cut quality gradings range from

  • Ideal Cut (0)
  • Excellent Cut (1)
  • Very Good Cut (2)
  • Good Cut (3 to 4)
  • Fair Cut (5 to 7)
  • Poor Cut (8 to 10)

See the light performance for yourself, and you will know immediately if you are happy with it or not.

Diamond Certification

A diamond certificate is documentation of a diamond’s quality by a reputable diamond grader, not the person selling you the diamond. Diamond certificates must be original and there are various security features to prove this.

the anatomy of the diamond