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Diamond Engagement Rings 101 – A Practical Guide to Buying Diamonds

As with any big purchase, shopping for the perfect engagement ring is about finding an option you love at a price you are happy with. As the bulk of an engagement ring’s value most often lies in its centre diamond, this is the ideal place to start. However, diamonds come in such a multitude of grading options, each with its own characteristics and, of course, price tag that many shoppers dread making the final call. Let’s cut out the nitty gritty and look at what diamond grading really means to you.

When the search for the perfect diamond starts, buyers inevitably learn the four C’s of diamond grading, namely cut, clarity, colour and carat weight. The international pricing structure of diamonds, called the Rapaport, assigns a per carat price for each size range of diamonds based on a particular colour and clarity combination. This structure in turn is divided in round brilliant cut diamonds and fancy cuts (every cut besides round brilliant).

Carat weight

Arguably the simplest grading to understand, the carat weight of a diamond by nature indicates its size. For your interest 1 carat equates to exactly 0.20 grams. A well cut 1.00ct round brilliant cut diamond measures approximately 6.50mm in diameter. Since the angles of a diamond have to fall within an ideal range to facilitate optimal refraction (sparkle), a 1.00ct stone with an unusually large or small diameter indicates a poor cut quality. For this reason diamonds grow in every dimension as they increase in carat weight, so a 2.00ct would not have double the diameter of a 1.00ct. The ideal 2.00ct round brilliant cut diamond actually has an optimal diameter of approximately 8.00mm.

Due to the rarity of larger, gem quality diamonds, prices become exponentially higher per carat as the weight of a single stone increases. 10 diamonds with a total weight of 1.00ct carats would therefore be a fraction of the price of an equivalent quality single stone with this weight.


Contrary to a common misconception the clarity and sparkle of a diamond are not related. Diamond clarity refers to the presence, or absence, of natural imperfections in a particular stone. These can be internal or on the surface of a diamond and range from almost undetectable irregularities in the crystal structure to highly visible black areas within an otherwise transparent stone.

While an IF (Internally Flawless) diamond has the ideal clarity, most higher to medium clarities appear flawless to the unaided (naked) eye. Diamond clarities are graded based on plotting visible phenomena at ten times magnification, which means a lot of the imperfections contributing to a particular stone’s clarity grading can only be seen at this level of magnification. In real life, when set in a ring, a lot of medium range clarities (e.g. SI1 or VS2) appear to be flawless and cost a lot less than a truly flawless diamond.  In some cases even lower clarities like SI3 or I1 can be eye clean, but this depends on the nature of the impurities and where they are located in the stone. When it comes to clarity, the best is always to see the stone in person and not only rely on the grading.


Generally diamonds are graded on a yellow tinted colour scale ranging from D, the whitest commonly found stones, to Z, which is a borderline fancy yellow diamond. Variations from this scale such as ECG gradings (equivalent tint intensity of colours besides yellow), fancy coloured diamonds and black diamonds are priced differently and most often according to their rareness.

High-end jewellery like the Mark Solomon Jewellers range is most often set with a combination of F, G and H colour diamonds which are considered fine white stones. A more affordable alternative would be to use I, J and K colour diamonds known as commercial whites. Although these two colour ranges fall within the white spectrum of the colour chart, the difference between a fine white and commercial white stone becomes evident with comparison.

Bear in mind any side diamonds used to enhance a centre diamond must be of the same or similar colour grade to ensure the best overall appearance of an engagement ring.


Although the cut quality of a stone influences its price to a lesser extent than its colour or clarity, investing in a well cut diamond means the stone is cut to optimally refract light i.e. sparkle. Diamond accompanied with a laboratory certificate gives you a breakdown of cutting angles and dimensions, which is valuable knowledge, but again, seeing the stone in real life is the only true way to judge its splendour.

As a rule of thumb fancy cut diamonds sell for about 20% to 30% less than round brilliant cuts of the same size, colour and clarity. This is useful knowledge to engagement ring shoppers as most designs meant for a round brilliant cut can be manufactured to accommodate a cushion or oval cut centre stone which would ensure a similar end result at a lower price.

To view the widest variety of loose diamonds South Africa has to offer, or for your obligation free consultation with one of our highly qualified jewellery designers, visit Mark Solomon Jewellers today. With over three decades committed to the highest standards of quality our showroom has become an iconic Cape Town jewellery destination. We pride ourselves in creating a range of high end diamond jewellery South Africa and the rest of our international clientele can enjoy for generations.