If you’re interested in buying a diamond in South Africa, there are a few things you need to be aware of and know about. Buying a diamond can be an incredibly complicated process and sometimes, diamond dealers and jewellery stores will bombard you with industry terms that are designed to confuse you. If a diamond dealer or jeweller sounds like s/he knows what he’s talking about, it doesn’t necessarily mean that you’re being sold the diamond that’s best for your requirements.

The gold standard of international diamond grading is the 4C’s, conceptualised and implemented by the Gemological Institute of America (the GIA). Diamonds are graded to a set of international standards regarding the cut, the colour, the clarity and the carat, collectively referred to as the 4C’s. Essentially, the 4C’s tell you what to visually expect in the diamond you are considering purchasing and they cover the most obvious features of the diamond. The 4C’s also affect the price of the diamond, with prices going up with better colours and clarities and larger carat weights.

Whilst the 4C’s are essential criteria to consider before making a final diamond buying decision, they don’t tell you the full story about the diamond. And this, friends, is where you could end up with a diamond that isn’t all it’s made out to be.

Why are we telling you this? Because buying a diamond engagement ring, in South Africa or anywhere else,  is an expensive exercise. Theoretically, it should be the only time you buy an engagement ring (although we all know that things don’t always pan out as planned), and to be honest, we don’t want you to get ripped off. Knowledge is power so, as far as we concerned, the more you know about what to look for in diamonds, the better off you’ll be when you commit to the purchase.

Yes, the 4C’s give you the basics of what to look for in the diamond, but it’s the bare minimum for you consider. The dimensions, proportions and shape of the diamond, are essential factors to look at, particularly when considering a fancy shape diamond (i.e. anything other than a round brilliant cut). Another thing to bear in mind is the fluorescence of the diamond that you’re considering. These are all factors that are listed on a GIA diamond certificate, but you might not realise the relevance of them and, if they’re not favourable, a diamond dealer might not even discuss them with you at all.

We’ll shed light on 3 factors that fall outside the scope of the 4C’s, but that can have a huge effect on the overall look of the diamond.

Diamond weight vs diamond size

Let’s start with the carat weight of the diamond. For round brilliant cut diamonds, it’s straight forward – if you’re looking at an excellent or very good cut diamond (which is what you should be looking at), a certain carat weight is going to have a certain diameter. The weight of a round diamond is determined by both its diameter and its depth. All you really see when the diamond is set in a ring is the diameter, the visual surface area.

For fancy shape diamonds, like an oval, emerald or pear cut for instance, you now have a length, width and depth that will contribute to the carat weight of the stone. As an example of how the three measurements interact with each other, consider the two emerald cut diamonds in the image below. The diamond on the left is 0.48ct, the diamond on the right is 0.56ct. These two diamonds are very close in carat weight, with only 0.08ct in weight between them. Yet, the diamond on the right looks significantly larger in size than the diamond on the left.

Buying a diamond in South Africa
These two diamonds have carat weights within 0.08ct of each other, but the visible size of each is very different.

If we ignore the carat weight of the diamonds, the millimetre measurements tell us a completely different story. The 0.48ct diamond measures 4.6mm (length) x 3.82mm (width) x 2.86mm (depth). The depth of the diamond is 74.9% of the width of the diamond.

The 0.56ct diamond measures 6.12mm (L) x 3.91mm (W) x 2.46mm (D). The depth of this diamond is 62.9% of the width of the diamond, a full 12% shallower than the 0.48ct diamond. Take a look at the picture below to see how much deeper, and thus how much heavier the 0.48ct diamond is relative to the 0.56ct diamond.

Trust the 4C's when buying a diamond
Have a look at how much deeper the diamond on the left is cut, compared to the diamond on the right. The deeper a diamond is, the heavier it will be.

Taking into account the millimetre size of a diamond is not just critical when it comes to the visual appeal of the diamond, it can also save you a significant amount of money. Diamond prices go up exponentially at key weights, at the one carat mark for example. Many people would love a one carat diamond, but they can come with a significant price tag. Sometimes though, a diamond in the heavy 0.90’s weight range will have similar, if not the same millimetre measurements as a 1 carat diamond – but at a much cheaper price.

As an example, consider the diamond in the photograph below, which we recently offered to a client who was looking for a 1 carat diamond. It’s a 0.95ct princess cut diamond that measures 5.45mm x 5.17mm (length x width). Another diamond that was available to them was a 1.01ct princess cut, measuring 5.27mm x 5.24mm. The 0.95ct diamond looks slightly bigger in person than the 1.01ct diamond, but it’s nearly 20% less than the 1.01ct diamond.

A 0.95ct princess cut diamond, recently purchased by a client of ours, with the same dimensions as a 1ct diamond.

That’s a huge price difference and would cover the cost of manufacturing a solitaire ring design with the diamond.

Diamond buying lesson 1: Look at the millimetre measurements of the diamond, not just the carat weight.

Diamond proportions

Oval cut diamonds are incredibly popular right now, and one of the most important factors to consider when buying an oval cut (or marquise, or pear cut) diamond is the length-to-width ratio of the diamond. Any diamond that is elongate in shape should be looked at in context of the proportions of the gemstone.

Recently, we had a client looking for a pear-cut diamond, and he was interested in two particular diamonds we offered him, a 0.61ct and a 0.70ct diamond. On paper, i.e according to the 4C’s, the 0.61ct diamond was a very desirable diamond at a very competitive price. The 0.70ct diamond was quite a bit more expensive and the client was unsure of this stone. In person however, the visual appeal of the stones showed a completely different story. The 0.61ct diamond had a length-to-width ratio of 1.42 (6.9mm long x 4.87mm wide x 2.95mm deep) whereas the 0.70ct diamond had a length-to-width ratio of 1.73 (8.13mm long x 4.71mm long x 2.78mm deep).

Essentially, the 0.61ct pear-cut diamond was short and fat, whereas the 0.70ct was longer and slimmer, giving a more elegant classic look on the finger. Being able to look at the diamonds in person gave our client the confidence to choose the best fit diamond for his needs.

As another example, consider the images below of two oval-cut diamonds. Both are of a similar weight; the diamond on the left is a 0.51ct diamond, the diamond on the right weighs 0.50cts. The 0.51ct diamond measures 6.35mm x 4.34mm and has a length-to-width ratio of 1.46. The 0.50ct diamond measures 5.67mm x 4.25mm and has a length-to-width ratio of 1.33mm.

buying an oval diamond in south africa
A 0.51ct oval diamond (left) vs a 0.50ct oval diamond (right). Look at the huge visual size difference, even though the carat weights are virtually identical.

There is no right or wrong set of proportions for a fancy shape diamond, and it’s mostly down to the individual to determine what is the most aesthetically appealing set of proportions. Some people may like the shorter and fatter look (like the 0.50ct diamond on the right), others may prefer the longer look of the 0.51ct diamond on the left. It’s entirely a personal choice, but know that it’s something that the basic 4C’s will not tell you, so you need to look a little closer at the diamond certificate.

As a final note on this topic, we also want to point out another factor contributing to diamond weight, one you may not even have ever heard about. Let’s go back to the 0.51ct and 0.50ct oval diamonds we’ve just mentioned.  The 0.51ct is much longer and slightly wider than the 0.50ct diamond (as you can see in the measurements above), but the carat weights are virtually identical. The depths of the diamonds are almost identical too, 2.82mm and 2.84mm respectively.

So why is the 0.50ct so similar in weight to the 0.51ct when it’s so much smaller?

The answer is hidden in the girdle of this diamond.

Diamond girle thickness
The girdle thickness of the 0.50ct diamond on the right (indicated by arrows) is significantly thicker than the left diamond girdle. This thicker girdle explains why the diamonds are so close in weight, yet so different in visual appearance.

The girdle is the thin perimeter of the diamond, separating the crown of the diamond (the top part) from the pavilion of the diamond (the bottom part). The girdle can vary in thickness from extremely thin to extremely thick, and ideally should be thick or slightly thick. In the case of this 0.50ct oval, the girdle is classified as “Very thick to Extremely thick”, which you can see easily on the side view of the diamond (above). So, much of the carat weight of this diamond is held in the girdle of the diamond, contributing to the overall smaller visual appearance of this diamond.

Diamond buying lesson 2: Look at the length-to-width ratio of a fancy shape diamond before buying it.

Diamond Fluorescence

Fluorescence in diamonds is an oft-misunderstood topic, and one that we’ve written about before. The GIA gives great insight into fluorescence and for the most part, fluorescence does not visually affect the diamond at all. Despite falling outside of the remit of the 4C’s, fluorescence is something you should be aware of and educate yourself on, before deciding whether it’s something acceptable to you in the diamond you’re purchasing, or whether you want to avoid it. The GIA lists the fluorescence of a diamond towards the bottom of their certificates, between the “Finish” and “Clarity Characteristic” ratings.

GIA diamond certificate
Essential information contained in a GIA diamond certificate also includes the fluorescence of the diamond, and the proportions of the stone (right hand side of the certificate).

A diamond with even faint fluorescence will be more competitively priced than a diamond with no fluorescence, thanks to industry bias that the diamond industry has developed. Market research has shown that often, the public is not concerned by fluorescence when purchasing diamonds, which means you can use the industry bias to your advantage regarding price points.

Very occasionally, fluorescence may impact the visual look of the diamond which you won’t know until you see the diamond in person. If a diamond has a milky or oily look to it, you’re seeing the effect of strong fluorescence and the diamond is going to be significantly cheaper to purchase.

Strong blue fluorescence (blue is the most common colour of fluorescence) can sometimes give lower colour diamonds (K, L, M, N colours etc) a slightly whiter look, which is advantageous. In other instances (like the example below), it can give a diamond an almost blue hue, which some people find attractive and unique. Fluorescence in diamond is a personal choice, but if you can’t have a look at a diamond in person before you purchase it, at least request comprehensive photographs and videos (under both natural and artificial light) to make sure you’re making the right decision.

Diamond buying lesson 3: Look at the fluorescence of the diamond you’re considering buying.

We hope this post has helped you understand the finer intricacies of the buying a diamond in South Africa. The 4C’s are a great guideline, but you have to look beyond the basics to fully understand your purchase. If at all possible, we recommend looking at diamonds in person before making a purchase, but if that’s not possible, you must have absolute trust in the person/business you’re buying a diamond from.

Take the time to read the Google and Facebook reviews on their business. As an almost exclusively online business, Katannuta Diamonds is committed to the utmost transparency when working with all of our clients, particularly those outside of Gauteng (and South Africa), where we are based. We work with many remote clients and sending photographs and videos of diamonds, alongside the diamond certificates, ensure that our clients know they are buying their perfect diamond, each and every time.

Have you got any questions about buying a diamond, or are you looking for a quote on a diamond? Reach out to us via our contact page, or via our Facebook or Instagram pages, and let us know how we can help you.

Clare Appleyard

M.Sc. (UCT); AJP (GIA)

Co-founder, Katannuta Diamonds.

Leave a Reply

Your email address will not be published. Required fields are marked *