The 4C's Of Diamonds — 1 Carat Edition (2026)

Carat, Colour, Cut, Clarity.

When you cross paths with your first diamond grading report during engagement ring shopping, it can feel overwhelming. A handful of characteristics are stated and graded using classifications that mean absolutely nothing at first glance.

To help buyers make sense of it all, the industry created a basic framework — the 4Cs: Carat, Colour, Cut, and Clarity. You'll find some version of this on 99% of jewellers' websites, and it's a genuinely useful starting point for understanding what drives a diamond's appearance and price.

The problem is that the standard 4C explanation floating around the internet is too diluted to be truly useful. 

Certain Cs become more or less important as the size of the diamond changes — clarity in particular can't be properly assessed without fixing the carat first. That's exactly what this guide does.

One thing to keep in mind: we operate in the upper tier of the local market. When I refer to "lower colour diamonds" in this guide, we're still firmly in shades of white — nothing murky or obviously tinted. Have a look at our Instagram to get a feel for the standard of work we do.

Minimum/Recommended Budget for a 1,00ct Diamond

Our diamond prices are excellent — so the figures below won't apply at most other jewellers. These are the minimums I'd recommend allocating to the diamond itself if you're set on a 1.00ct stone.

Mined diamonds:

• Round, Oval & Pear — R55,000

• Emerald & Radiant — R45,000

• Cushion — R40,000

Lab-grown diamonds:

• Budget R6,000 – R8,000 across all shapes

One thing I'll say plainly: a visually beautiful 0.90ct diamond beats a compromised 1.00ct every single time. Over-reaching on carat at the expense of cut, colour, or clarity will not give you a more impressive ring — it'll give you a larger disappointment.

First C: Carat

Carat is simply a measure of weight — 5.00ct equals one gram.

A 1.00ct diamond is regarded as an aspirational benchmark and sits above the average centre stone size in the South African market. That said, the bulk of what you see on Pinterest and Instagram sits closer to the 2–3ct range — keep in mind that most jewellers deliberately use larger stones in photo shoots.

The good news is that a 3.00ct design she has her heart set on can often be stunningly executed with a 1.00ct–1.30ct mined diamond. And if it's the full glamour of those Pinterest boards you're after, a lab-grown 2–3ct diamond might be the smarter move — exceptional size, exceptional quality, without the exceptional price tag.

The best way to get a real feel for sizes is to visit one of our studios — Pretoria, Sandton, or Cape Town — and see them in person. If it's a couple's trip, have her try on a few sizes. What looks large on a screen often feels different on the hand.

Second C: Colour.

Diamond colours start at D (colourless) and trickle down the alphabet to Z (prominently yellow). Your preference is personal and worth exploring in person — but as a starting point, here are the minimum colours for a diamond to appear white by shape:

• Round & Emerald — I

• Cushion, Pear, Oval & Radiant — H

If you're comfortable with a very slight hint of warmth, knocking down a shade or two is perfectly fine — you'll still be in white-ish territory. But the colours above are safe bets, since most ladies prefer a diamond free from any visible colour.

If you're after a truly colourless diamond and mined prices at the top end feel steep, it's absolutely worth looking at lab-grown options — which typically sit in the D–F colourless range at a fraction of the cost.

At 1.00ct, the diamond is the focal point of the ring. An obvious colour compromise will detract from the final result.

How low can you go?

Round brilliant K colour diamonds — particularly those with strong blue fluorescence, which improves the perceived colour — are great buys and worth considering if size is your priority.

Ovals and cushions are a different story. These shapes concentrate colour toward the edges of the stone. It's the same reason rare coloured diamonds at auction — blues, reds, purples — are almost always cut into ovals or cushions: to intensify the colour. 

In practice, a K colour oval or cushion will appear approximately two shades lower than a K colour round brilliant. For oval and cushion shapes, I draw the line at I.

At the top end — D, E, F colours

Full transparency: I've been working with diamonds daily for almost two decades. There is no way I could distinguish a D colour from an F colour out in the world, away from a controlled environment — loose, unset, under white light, directly next to each other on a white surface.

F through I is where you'll find the best appearance-to-price ratio in mined diamonds. Every one of those grades will be a shade of white — no prominent yellow, no brown. 

If you're considering a lab-grown diamond, there's no reason to drop below F colour.

Third C: Cut (Regardless of size, this is the most important C)

Diamond cut is often confused with diamond shape — round, oval, square, and so on. You'll find this error in far too many 4C guides, so let's clear it up.

Shape is what the diamond looks like from above. Cut is about craftsmanship — the precision with which the diamond's facets have been placed and proportioned. Think of those facets as internal mirrors, reflecting light in and out of the stone. Get the proportions right and you get maximum brilliance. Get them wrong and even the most expensive diamond looks like a dull piece of glass.

Through decades of research, scientists and gemologists have determined the optimal facet placement for modern brilliant cuts. The GIA took this further — using optical measuring instruments to compare diamonds against over 38.5 million proportion combinations, then issuing a cut grade via their FacetWare technology:

• Excellent — optimal light reflection and refraction

• Very Good — very close to perfect, indistinguishable to most eyes

• Good — a broad grade these days; some are fine, some are poor. Rather avoid

• Fair — no

• Poor — no

Your 1.00ct diamond is the centrepiece of the ring. Cut is non-negotiable — size, colour, and clarity cannot rescue a poorly cut stone.

Excellent cut doesn't carry a massive premium over a well-cut Very Good. That small difference is worthwhile insurance — take it.

Fourth C: Clarity (Greatly dependent on the size of the diamond)

While researching other 4C guides I was consistently baffled by one glaring omission — the size of the diamond plays a tremendous role in how clarity should be assessed. You simply cannot evaluate clarity without fixing the carat first.

Clarity refers to the level and nature of inclusions and imperfections in a diamond. It's graded at 10X magnification by human beings. Magnify any diamond by 100X and you'll find impurities — don't let "Flawless" appeal to the poet in you.

No two diamonds are alike, and the standards for any given clarity grade carry some subjectivity. The grader considers the location of inclusions, their type, their number, and the effect they have on the stone's appearance.

As a rule of thumb, VS2 and better has traditionally been a reliable guarantee that your diamond will appear flawless to the naked eye — referred to as eye-clean. Nobody walks around with a magnifying glass at parties. Eye-clean is the benchmark. Rather put your budget toward colour or size while keeping cut at Very Good or Excellent.

Why size changes everything

A round diamond has 58 facets. In a smaller stone those facets are densely packed — light bounces around rapidly and minor inclusions are easily masked. As the diamond gets larger, the facets spread out, it becomes easier to look into the heart of the crystal, and imperfections become more visible.

To illustrate — we 3D scaled a diamond to an X5 size:

If you're buying a 0.50ct diamond, even some SI2 stones will appear eye-clean. Scale that same 0.50ct up to a 2.00ct and you're hit with two problems at once — the inclusions are physically larger, and the less concentrated facet layout makes them easier to spot.

At 1.00ct, most VS2 diamonds will be eye-clean — but only if they've been accurately graded. This is where the integrity and experience of your jeweller matters enormously.

Let’s allow a 3% inclusion in a 0,50ct diamond, and then see how this same percentage looks on a 1,00ct diamond and even on a 2,00ct. It becomes significantly more visible as diamond size increases.

We surveyed 800 ladies in South Africa and 82% were clear: visible inclusions are a dealbreaker.

So… VS2 and better. That's the line.

Why I think we’re the best fit for 99% of 1,00ct buyers

Most jewellers will tell you their core competence is pricing. You'll see bargain bin ads swearing they're the cheapest in the world. They're not — and even if they were, it misses the point entirely. Two diamonds can share identical 4C grades on paper while one visually outperforms the other by a considerable margin.

Our core competence is the meticulous way we source diamonds. We stick to GIA and IGI certification, but we will never buy a diamond on the certificate alone — not in a million years.

We source exclusively from the largest diamond cutting and polishing factories in the world. They have the expertise, the experience, and the capital to finish diamonds to the highest standards. For every diamond we consider, we request HD video and imaging before making a decision. With VS gradings becoming broader than they were a few years ago, we eliminate VS2 and even VS1 options daily that simply won't be eye-clean.

Those visibly included VS2 diamonds are cheaper. Sourcing cheap diamonds is easy. But even if you're comfortable with a compromised stone — we're not, and we won't sell it.

That's where we lose the last 1% of buyers. A price I'll gladly pay.

What our clients know is that we've spent hours sifting through hundreds of diamonds before making a single recommendation. We don't compromise on cut. We don't compromise on clarity. We don't hide behind certificates. Every option we show you has been checked by multiple sets of experienced eyes.

Come and see us at any of our three studios — Pretoria, Sandton, or Cape Town. Even if you have no immediate buying plans, you're welcome to come in for a coffee. These decisions take time and that's completely understood.

Feel free to reach out directly at johan@poggenpoel.com — I'm always happy to help.

Johan Poggenpoel