4C Education
The Four Cs of
Diamond Quality
Everything you need to understand a diamond — and make a choice you'll cherish forever.
Know What
You're Choosing
The 4 Cs — Cut, Colour, Clarity, and Carat — are the universal language of diamond quality. Understanding them puts you in control of the most important decision in your purchase.
Diamonds are among the most complex objects of desire in the world. Two stones of identical size can have wildly different value and beauty — and the difference comes down entirely to these four characteristics. At ZIZOV, our non-commissioned experts will walk you through every detail in person, but this guide gives you the foundation to arrive informed and confident.
Every diamond we sell is independently graded by GIA, IGI, or HRD — the world's three most respected gemological institutes. The certificate accompanying each stone is your guarantee that what you see is precisely what you get.
Cut
The most important of the 4 Cs — responsible for a diamond's brilliance, fire, and scintillation.
Cut does not refer to the shape of a diamond — it refers to how well the stone's facets interact with light. A perfectly cut diamond will return light through its crown in a breathtaking display of brilliance and fire. A poorly cut stone, regardless of its size or colour, will appear dull and lifeless.
The quality of cut is determined by proportions, symmetry, and polish. The GIA grades diamond cut on a scale from Excellent to Poor — and at ZIZOV, we work exclusively with Very Good to Excellent cut diamonds to guarantee that spark you can feel across a room.
The Difference Between Alive and Ordinary
Two diamonds with identical colour and clarity grades will look completely different if one is cut to Excellent proportions and the other is not. Cut is the one characteristic that is entirely within human control — and the one that most dramatically affects beauty.
- Always prioritise cut grade above all other characteristics
- An Excellent cut G-colour diamond outperforms a D-colour Fair cut
- ZIZOV only sources Very Good and Excellent cut stones
- Popular shapes: Round Brilliant maximises brilliance; Oval, Cushion, and Emerald each offer a distinctive aesthetic
Colour
In white diamonds, the less colour, the higher the value. The GIA scale runs from D (colourless) to Z (light yellow or brown).
A chemically pure diamond has no hue — like a drop of pure water. In practice, most diamonds contain trace elements of nitrogen that produce a subtle yellow or brown tint. The GIA colour grading scale assigns letters D through Z to measure the degree of colour present in a white diamond.
The difference between adjacent grades is virtually invisible to the untrained eye, but has a significant impact on price. At ZIZOV, we typically work with G through J colour diamonds — stones that appear colourless to the naked eye when set in a ring, at a significantly more accessible price point than D–F grades.
How Metal Choice
Changes Everything
The metal you set your diamond in has a profound effect on how colour appears. A G-colour diamond in a white gold or platinum setting will appear colourless — the same stone in a yellow gold setting will actually look whiter, because the warm gold absorbs surrounding colour.
- White gold or platinum: choose G–H for the best value-to-appearance ratio
- Yellow or rose gold: you can go down to I–J without visible difference
- Fancy coloured diamonds (yellow, pink, blue) are graded on a completely separate scale
- Lab-grown diamonds are available in the same colour grades as natural stones
Clarity
A measure of the natural inclusions and blemishes within a diamond — virtually all diamonds contain them, formed over millions of years under the earth.
Diamonds form under extreme heat and pressure, and almost all carry tiny internal characteristics called inclusions and external ones called blemishes. The GIA clarity scale evaluates these characteristics under 10x magnification and assigns a grade from Flawless (no inclusions visible) to Included (inclusions visible to the naked eye).
The key concept for buyers is "eye-clean" — a stone where no inclusions are visible to the naked eye at normal viewing distance. At ZIZOV, our experts help you identify the sweet spot between a visually perfect stone and unnecessary spending on characteristics you will never see.
Eye-Clean is the
Golden Standard
Paying for a Flawless diamond when its characteristics are indistinguishable from a VS2 to the naked eye is rarely worth the premium. Our experts at ZIZOV will always show you two or three stones side by side so you can see the real difference — and make an informed choice.
- VS1–VS2: the ideal balance of quality and value
- SI1 can be eye-clean in round brilliants — less so in step-cut shapes like Emerald
- Always view the actual stone, not just the certificate grade
- Our team evaluates every stone's inclusions for position and impact before recommending it
Carat
Carat is the unit of weight for diamonds. One carat equals 0.2 grams. Larger stones are exponentially rarer — and priced accordingly.
Carat weight is the most misunderstood of the 4 Cs, because it measures weight — not size. Two diamonds of equal carat weight can look very different in diameter depending on how they are cut. A well-cut 1.00ct round diamond will appear larger than a 1.10ct stone with a deep cut that hides weight below the girdle.
The most important insight: price increases exponentially at magic numbers — 0.50ct, 0.75ct, 1.00ct, 1.50ct, 2.00ct. A stone of 0.95ct will appear almost identical to a 1.00ct stone but can be significantly less expensive. Our experts will always show you both options so you can decide with full information.
Getting More
For Your Budget
Two strategies consistently give more diamond for the money. First, choose a "just under" stone — a 0.90ct or 0.95ct appears nearly identical to a 1.00ct but often costs significantly less. Second, choose a shape with a larger face-up appearance — an Oval, Pear, or Marquise cut typically looks 10–15% larger than a Round Brilliant of the same weight.
- 0.90–0.97ct appears the same as 1.00ct to the naked eye
- Oval and Pear shapes have a larger diameter-to-weight ratio than Round
- Lab-grown diamonds allow you to select a significantly larger stone within the same budget
- Always weigh up all 4 Cs together — a 2.00ct SI2 Fair cut can look worse than a 1.20ct VS1 Excellent
The Importance of Independent Certification
A diamond without a certificate from a reputable independent gemological institute is a diamond without a verifiable identity. Every stone ZIZOV sells comes with its original certificate.
Gemological Institute of America
Widely regarded as the world's most respected and consistent diamond grading authority. GIA created the 4 Cs system and the international diamond grading standard — their certificates are accepted everywhere as the gold standard of diamond evaluation.
International Gemological Institute
One of the largest independent gem certification laboratories in the world, with a major presence in Antwerp. IGI is the most widely used certifier for lab-grown diamonds and is fully accepted by the global trade as a mark of quality and integrity.
Hoge Raad voor Diamant
The Antwerp Diamond Council — founded here, in the heart of the world's diamond capital. HRD certificates are deeply respected in Europe and across the global trade, and carry a particular significance for ZIZOV as fellow Antwerp institution. HRD certifies both natural and lab-grown diamonds to the highest standard.
Your Guarantee of Truth
A gemological certificate is an independent, objective record of a diamond's exact characteristics — verified by trained experts using specialised equipment under controlled conditions. It ensures that the stone you receive is precisely what you were shown, and provides permanent documentation of its quality and value.
Guided by
Expertise, Not Commission
Our non-commissioned experts will sit with you and walk through every characteristic of any stone you're considering — comparing grades side by side, explaining the real-world visual impact, and helping you find the best stone for your specific budget and priorities.
We stock certified natural and lab-grown diamonds across every cut, colour, clarity, and carat range. Whatever your vision — from a delicate daily-wear piece to a once-in-a-lifetime engagement ring — we'll help you find the one.
Ready to Choose
Your Perfect Diamond?
Visit our Antwerp showroom or book a private consultation — our experts will guide you through every C in person, with real stones in your hands.