Diamond Clarity
The most important factor in a diamond's beauty — how light performs within the stone.
Understanding Diamond Clarity
Natural diamonds form under tremendous heat and pressure deep within the earth — typically 150 to 200 kilometres below the surface, at temperatures above 1,000°C. This violent process almost always creates internal characteristics called inclusions and surface characteristics called blemishes. Together, they determine a diamond's clarity grade.
No two diamonds have the same pattern of inclusions. Like fingerprints, these natural characteristics make each stone unique. A clarity grade measures how visible these characteristics are under standard 10× magnification — not whether the diamond is "perfect," but how closely it approaches perfection.
Most inclusions in diamonds sold at Diamantwerp are invisible to the naked eye. The key is understanding which grades offer genuine visual differences and which differences only matter on paper — and under a loupe.
Key insight: "Eye-clean" is the goal. A VS2 or SI1 diamond that appears clean to the naked eye offers outstanding value — the inclusions exist but are invisible without 10× magnification. You're paying for what you can't see.
The Clarity Grade Scale
The GIA diamond clarity scale has six categories and eleven grades. It was developed to provide a universal standard for communicating the degree to which a diamond is free from inclusions and blemishes when examined under standard 10× magnification.
How Clarity Is Graded
Gemologists examine diamonds under standard 10× magnification (a jeweller's loupe or microscope) and evaluate five factors that determine the final clarity grade:
Size — larger inclusions have a greater impact on the grade. Number — the more inclusions present, the lower the grade. Position — inclusions directly under the table (centre of the diamond) are more visible than those near the girdle. Nature — some inclusion types (like feathers reaching the surface) are more significant than internal crystals. Relief — how much contrast the inclusion has against the surrounding diamond.
The grading is performed face-up — looking through the table — because that's how a diamond is seen when worn. The grader considers the overall impression at 10× magnification. Higher magnification may reveal additional characteristics, but these do not affect the grade.
Diamantwerp note The 10× standard is universal across GIA, HRD Antwerp and IGI. If an inclusion is invisible at 10× magnification, it does not affect the clarity grade regardless of what higher magnification reveals. This is why FL and IF grades are so exceptionally rare.
Clarity Grading: GIA vs HRD Antwerp vs IGI
All three laboratories Diamantwerp works with use the same clarity scale, but there are subtle differences in methodology and reputation for strictness:
| Grade | Description | Light Performance | Rarity |
|---|---|---|---|
Excellent |
Maximum fire and brilliance. Reflects nearly all light that enters the diamond. | Performance: Outstanding | Rarity: Top ~3% |
Very Good |
Reflects most light. Minor deviations from excellent proportions. | Performance: Very High | Rarity: Top ~15% |
Good |
Reflects a majority of light. Noticeable but not significant brilliance loss. | Performance: High | Rarity: Top ~25% |
Fair |
Some light escapes through sides or bottom. Still a quality diamond but visibly less brilliant. | Performance: Moderate | Rarity: Top ~35% |
Poor |
Significant light loss. Diamond appears dull and lifeless to the naked eye. | Performance: Low | Rarity: — |
Diamantwerp note
Both GIA and HRD include a clarity plot on their reports — a diagram showing the approximate size, type and position of significant inclusions. This is invaluable when comparing diamonds, especially at SI1 and SI2 grades where inclusion placement determines whether a stone is eye-clean.
Common Types of Inclusions
Not all inclusions are created equal. The type of inclusion affects both its visibility and its impact on the diamond's beauty and structural integrity:
| Grade | Description | Light Performance | Rarity |
|---|---|---|---|
Excellent |
Maximum fire and brilliance. Reflects nearly all light that enters the diamond. | Performance: Outstanding | Rarity: Top ~3% |
Very Good |
Reflects most light. Minor deviations from excellent proportions. | Performance: Very High | Rarity: Top ~15% |
Good |
Reflects a majority of light. Noticeable but not significant brilliance loss. | Performance: High | Rarity: Top ~25% |
Fair |
Some light escapes through sides or bottom. Still a quality diamond but visibly less brilliant. | Performance: Moderate | Rarity: Top ~35% |
Poor |
Significant light loss. Diamond appears dull and lifeless to the naked eye. | Performance: Low | Rarity: — |
Table
The large flat facet on top — the main window through which light enters and exits. Table percentage (table width relative to total diameter) is a key proportion.
Crown
The upper portion between the table and girdle. Crown angle affects the balance between brilliance and fire — too steep or too shallow disrupts light return.
Girdle
The widest edge where crown meets pavilion. An extremely thin girdle risks chipping; an extremely thick girdle hides carat weight without adding visual size.
Pavilion
The lower portion from girdle to culet. Pavilion depth is critical — too deep and light escapes the sides; too shallow and it leaks through the bottom.
On any GIA or HRD clarity plot, you'll see these characteristics marked using standardised symbols. Green symbols represent internal inclusions; red symbols represent surface blemishes. Understanding these helps you read a diamond certificate like a professional.
Eye-Clean Diamonds: The Practical Standard
"Eye-clean" is an industry term meaning no inclusions are visible to the naked eye when the diamond is viewed face-up at a normal viewing distance (approximately 15–20cm). This is not an official laboratory grade — it's a practical assessment that matters far more to most buyers than the technical clarity grade.
The eye-clean threshold varies by diamond shape because different facet patterns either hide or reveal inclusions differently:
Round brilliant diamonds are the most forgiving because their intense brilliance and fire effectively mask most inclusions. Elongated shapes like oval, marquise and pear can show inclusions at the tips. Step-cut shapes like emerald and Asscher have large, open facets that act like windows — making even minor inclusions more visible.
Our Recommendation
For the best balance of beauty and value, we recommend VS2 or SI1 clarity grades for most buyers. These diamonds are eye-clean and allow you to maximise your budget on cut quality — which has a far greater impact on how your diamond actually looks.
If you're choosing a step-cut shape like emerald or Asscher, we recommend staying at VS2 or higher. Their large, open facets make inclusions more noticeable compared to brilliant cuts.
For diamonds above 1.5 carats, consider moving up one clarity grade from what you'd choose in a smaller stone. The larger surface area makes inclusions slightly more apparent.
With our prices up to 75% below retail, you can invest in the clarity grade that gives you genuine peace of mind without stretching your budget. Browse our collection or contact us for personal advice.
COMMON Questions
Frequently Asked Questions
What is diamond clarity?
Diamond clarity measures the presence of internal inclusions and external blemishes in a natural diamond. The fewer and smaller these characteristics, the higher the clarity grade — and the rarer the stone.
What are the diamond clarity grades?
The clarity scale runs from Flawless (FL) to Included (I1–I3). In between are Internally Flawless (IF), Very Very Slightly Included (VVS1–VVS2), Very Slightly Included (VS1–VS2), and Slightly Included (SI1–SI2). GIA, HRD Antwerp and IGI all use this same scale.
What does "eye-clean" mean?
An eye-clean diamond has no inclusions visible to the naked eye when viewed face-up at a normal distance. Many VS2 and SI1 diamonds are eye-clean, offering excellent value compared to higher clarity grades with no visible difference in beauty.
What is the best clarity grade for the money?
For most buyers, VS2 or SI1 offers the best balance of quality and value. These grades are typically eye-clean and cost significantly less than VVS or Flawless diamonds. Put the savings toward a better cut or larger carat weight.
Do inclusions affect a diamond's sparkle?
Minor inclusions in the VS and SI range rarely affect brilliance. However, large or dark inclusions in I1–I3 diamonds can block light and reduce sparkle. Cut quality has a far greater impact on brilliance than clarity in most cases.
Does diamond shape affect how visible inclusions are?
How is diamond clarity graded?
Gemologists examine diamonds under 10× magnification to identify inclusions and blemishes. They assess the size, number, position, nature and relief of these characteristics. The grade is determined by how easily they can be seen under magnification.
