The quality of a diamond is characterised by the four C's: Cut, Colour, Clarity, and Carat weight. The most important characteristic is the Cut, which determines the sparkle of the diamond, followed by the Colour of which colourless is prefered. It's usually best to start your diamond search by the Cut and Colour. Then, adjust your budget accordingly with the Clarity and Carat.
This is the most important characteristic of a diamond, because it’s the most visible to the naked eye. Not to be confused with the actual shape of the diamond, the cut refers to the amount of sparkle, and is determined by the depth and width ratio of the diamond. The better the cut, the more sparkle.
Cut is rated from Poor to Excellent. A poor cut diamond can appear dull, regardless of how good the clarity and colour is. Cut grades are only available on round brilliant cut diamonds.
OUR RECOMMENDATION - We recommend choosing a Very Good or Excellent cut
Colour is the second most important characteristic of a diamond, and determines if it’s purely colourless or has a noticeable yellow tinge.
Graded from D (completely colourless) to Z (very yellow). D - F won’t show any visible difference to the naked eye. You’ll start to see a yellow tinge from grade G onwards, but only very slight, which means it can be a good choice to maximise your budget.
OUR RECOMMENDATION - We recommend choosing D to F.
This refers to the absence of imperfections within the diamond, known as ‘inclusions’. Inclusions are tiny crystals formed in the diamond, but luckily most of these are only visible under the microscope. Clarity is the third most important characteristic of a diamond.
Graded from Flawless to I3 (heavily included), choosing a diamond between VS2 (Very Slightly Included) to SI1 (Slightly Included) is a good choice to maximise your budget, because even at these grades you’ll only be able to see inclusions (possibly with some effort) under a 10x magnification. When it comes to your budget, you’ll have a visibly nicer ring by choosing a better cut and colour rather than better clarity.
OUR RECOMMENDATION - We recommend choosing VS2-SI1 for a Brilliant cut diamond (Round, Princess, Radiant, Pear, Oval, Marquise, Heart & Cushion cut) and VVS2-VS1 for a Step cut diamond (Emerald & Asscher cut)
The diamond carat refers to the weight of the diamond, and not necessarily the size (which is a common misconception). The cut, along with the carat, will determine how large the diamond appears. Diamonds with a lower carat will appear larger with a higher cut (Very Good or better) because the sparkle is more prominent.
Some weights are considered "magic sizes" – half carat, three-quarter carat, and carat. Visually, there's very little difference between a 0.99 carat diamond and one that weighs a full carat. But the price differences between the two can be significant.
You should also consider the finger size of the wearer. For smaller finger sizes, a smaller carat can still appear quite large.
Lastly, the ring setting should also be taken into account, as larger carat diamonds (for example 2ct and above) may need a particular style.
OUR RECOMMENDATION - We recommend choosing the carat weight and size of diamond which best suits your budget once all of the four C's have been concidered.
A diamond with fluorescence means it may have a milky or hazy appearance under UV light.
Whilst non-fluorescent diamonds are considered ‘purer’ and therefore more expensive, it’s highly debatable whether fluorescence has any noticeable impact to the naked eye, given this is only visible under UV light.
The prices can vary greatly between fluorescent and non-fluorescent diamond, and in some cases a lower rated colour can be enhanced or improved by fluorescence, making it a potential choice to maximise your budget.
OUR RECOMMENDATION - We recommend non-fluorescent diamonds; however, when it comes to this characteristic, there is some subjectivity and may ultimately come down to preference.
Like getting an independent survey when buying a house, you should only buy a diamond that has been certified. The most reliable diamond certifications come from the Gemological Institute of America (GIA). They are renowned for their thorough, detailed and highly accurate certificates.
The GIA Diamond Grading Report contains scientifically determined information on diamond shape, Clarity, Color, Cut, Carat weight, proportions and finish. It also identifies any known treatments. Other reports from other entities have since made their way into the marketplace, but GIA is the most recognised.
OUR RECOMMENDATION - We recommend GIA certified diamonds.
For more information on the Diamond 4C's
All images are provided by the GIA 2017