Les 4C du diamant : taille, couleur, pureté et carat
The 4Cs of diamonds are the four internationally recognized criteria used to assess diamond quality: Carat (weight), Clarity (purity), Color and Cut. Developed by the GIA, this grading system allows diamonds to be compared using objective standards. Beyond the 4Cs, however, the trained eye and experience of a diamond expert remain essential to appreciating a stone's beauty and finding the best balance between quality and price.
The attestation of the 4C's of Carat, Color, Clarity, and Cut, if supported by a recognized Certificate, is indispensable as a guarantor, protecting against arbitrariness.
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De Hantsetters, diamonteers since 1888
The C of Carat - Diamond Weight and Its Impact on Price
Carat is the unit used to measure a diamond's weight: 1 carat equals 0.20 grams. Carat weight does not directly determine a diamond's visible size, which also depends on its proportions and shape.
Larger diamonds are generally rarer and more valuable when other quality factors are equal. Prices increase non-linearly, particularly around popular weight thresholds such as 0.50, 1 or 2 carats.
Our diamond expert's advice: Start by visualizing different diamond carat sizes on a hand, neckline or ear to determine the look you prefer and the corresponding carat weight.
Visualize different carats of diamonds on a hand, a bust, an ear
Compare carat sizeThe C in Clarity - Diamond Purity and Inclusions
Diamond clarity refers to the presence and visibility of internal inclusions or small surface characteristics. Gemological laboratories assess clarity under 10× magnification.
The international clarity scale ranges from IF (Internally Flawless), with no internal inclusions visible under 10× magnification, to I (Included), indicating more significant inclusions. Between these two grades are VVS, VS and SI.
Our diamond expert's advice: a carefully selected VS or even SI diamond can appear perfectly clean to the naked eye. The position and nature of inclusions matter just as much as their number.
For expert guidance in selecting a diamond based on the number, location and nature of its inclusions, please do not hesitate to contact us directly.
The C of Color - Diamond Color and the D-to-Z Scale
The color of a white diamond is graded on a scale from D to Z. Diamonds graded D, E and F are considered colorless, while grades G to J show very slight tint, often difficult to notice with the naked eye.
The closer a diamond is to D, the rarer it is. Lower grades show increasingly visible warm or yellowish tones.
Our diamond expert’s advice: for an excellent balance between beauty and budget, G or H color grades are often a very good choice, especially when the diamond has a high-quality cut.
The C in Cut - The Key to a Diamond's Brilliance
Diamond cut determines how effectively a diamond reflects and returns light. Unlike carat weight, cut refers to the quality of its proportions, symmetry and polish.
For round brilliant diamonds, the GIA uses five cut grades: Excellent, Very Good, Good, Fair and Poor. A well-executed cut enhances brilliance, fire (colored flashes of light) and scintillation.
Our diamond expert's advice: prioritize Excellent or Very Good cut grades. A beautifully cut diamond can appear more brilliant than a heavier stone with less favorable proportions.
How to Balance the 4Cs of Diamonds Within Your Budget
The 4Cs of diamonds should always be considered together: a larger diamond is not necessarily more beautiful than a smaller, better-cut stone.
To make the most of your budget, prioritize an Excellent or Very Good cut, a G to H color grade, and VS clarity, or even SI1 if the inclusions are not noticeable to the naked eye.
Our diamond expert's advice: focus on the balance between brilliance, color, clarity and carat weight. Two diamonds with similar grades can look noticeably different, highlighting the value of expert assessment.
Depending on your budget, however, you will need to set priorities. Experience has shown us that these priorities vary depending on our clients’ personalities. To summarize, we have identified three main types of approaches, which are explained below.
1. Prioritizing Carat Weight and Visual Impact
To achieve a larger-looking diamond within your budget, consider SI1 or even SI2 clarity, provided the inclusions are discreet to the naked eye and do not affect the stone's beauty. Their position deserves particular attention.
2. Seeking Perfection
For those who value rarity, prioritize D or E color, IF or VVS clarity, and an Excellent cut. This combination offers exceptional characteristics, naturally at a higher price.
3. Finding the Best Balance Between Quality and Price
For an attractive balance between beauty and budget, we often recommend F to G color, VS clarity, or carefully selected SI1, combined with an Excellent or Very Good cut.
The Diamond Expert's Eye: Beyond the 4Cs
Whatever your priorities, cut quality remains essential: it enhances a diamond's brilliance, fire and scintillation. Two stones with similar grades can display noticeable differences in beauty.
Since 1888, our experience as diamond experts has taught us that beyond grades and certificates, the most beautiful diamond is ultimately the one that captures your heart.
The 3 expressions of light
A diamond's sparkle is more than just its brilliance. It results from three complementary optical effects: brilliance, fire and scintillation. Closely linked to cut quality, these effects reveal a diamond's beauty and its ability to interact with light.
Brillance
The white light returned to the eye by a diamond. A well-executed cut maximizes light return, giving the stone its brightness.
Fire
The colored flashes created by the dispersion of light within the diamond, producing beautiful rainbow-like reflections.
Scintillation
The flashes of light and contrasting patterns visible as the diamond, light source or observer moves.
GIA, HRD and IGI diamond certificates
Explore our guideWhy Is Diamond Certification Essential for Evaluating the 4Cs?
A diamond grading report issued by an independent laboratory such as GIA, HRD or IGI documents the 4Cs: carat weight, color, clarity and cut. It provides an essential reference for comparing diamonds with confidence and transparency.
At i-diamants, we favor diamonds accompanied by recognized gemological reports, complemented by the experience and trained eye of a diamond expert.
Frequently Asked Questions About the 4Cs of Diamonds
Which of the 4Cs Is the Most Important?
Cut plays a crucial role in a diamond's brilliance. However, the best choice depends on the balance between cut, color, clarity and carat weight.
Can You See the Difference Between Diamonds with Different Grades?
Yes, but not always with the naked eye. Some differences in color or clarity are barely noticeable. Cut quality and visual examination remain essential.
Are the 4Cs Enough to Choose a Diamond?
The 4Cs provide an objective foundation, but they do not tell the whole story. Proportions, fluorescence and the location of inclusions also deserve expert consideration.
Do Diamonds with Identical 4Cs Have the Same Price?
Not necessarily. Differences in cut details, fluorescence, inclusion characteristics and market conditions can affect prices even when the four grades are identical.
De Hantsetters, diamonteers since 1888
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Contact us nowWe recommend the following 4 selections
To help you choose, we recommend 5 categories of diamonds that correspond to different purposes: Volume (maximizing weight), Balance (compromise weight and quality), Perfection (maximizing quality), Cut of heart (the i-diamants recommendation), Promotion (one-time price offer).
Volume effectmaximize the weight of the diamond relative to its price, I-J color and SI1-SI2 clarity
Choice of balancefavor a good balance of color / clarity: F-G / VS1-VS2
Perfectionmaximize the quality of the diamond with the best criteria of color and clarity: D IF
Favorite's choicediamond selected by i-diamants for its shine, D-E color, VS1 clarity, cut criteria all rated
Carats / Diamond weight
Move the diamond weight slider and view the rendering on a hand, chest or ears.
On the photo above, you can view different diamond diameters on a hand, by moving the slider. The fingertip of this hand is a size 53 (a measure quite common and which corresponds to an inner diameter of 1.68cm for the ring). The diameter of a diamond is proportional to its weight in carat (ct). The higher the weight, the larger the diamond. Carat is another unit of measurement of weight (1 carat = 0.2 gram).
On the photo above, you can view different diamond diameters on a woman's neck. The diameter of a diamond is proportional to its weight in carat (ct). The higher the weight, the larger the diamond. Carat is another unit of measurement of weight (1 carat = 0.2 gram).
On the photo above, you can view different diamond diameters on a woman's ear. The diameter of a diamond is proportional to its weight in carat (ct). The higher the weight, the larger the diamond. Carat is another unit of measurement of weight (1 carat = 0.2 gram).
Carat
mm (Approx.)
0,30 Ct
4,30 mm
0,40 Ct
4,60 mm
0,50 Ct
5,00 mm
0,70 Ct
5,70 mm
1,00 Ct
6,30 mm
1,25 Ct
6,90 mm
1,50 Ct
7,30 mm
Equivalence for round brilliant diamonds
Examples of different diamond measures
0,30 Ct
0,50 Ct
0,80 Ct
1,00 Ct
1,50 Ct
Diamond colours
Our recommandation
We recommend diamonds with a white hue between D (exceptional white+) and H (white) because the whiteness of the diamond increases its brilliance. From color grade I and J (slightly tinted) onwards, diamonds are slightly yellow-tinted: avoid on white gold and acceptable on yellow gold.
D-EExceptional white
F-GExtra white
HWhite
I-JSlightly tinted
K-MTinted white
N-ZVery tinted
Diamond clarity
Our recommandation
We recommend that you avoid choosing a Pique diamond, because inclusions are easily seen with the naked eye, alter the brilliance and can even weaken the stone. The clarities included in VS and SI1 are the most recommended , unless you have the budget to let yourself be tempted by IF or VVS clarities, which sign the diamond in its highest dimension: that of purity.
IFPure
VVSVery very small inclusion(s)
VSVery small inclusion(s)
SISmall inclusion(s)
PIncluded
IF : Pure
No inclusion inside the stone
VVS1 VVS2 : Very very small inclusion(s)
Very difficult to see with a 10X magnifying glass
VS1 VS2 : Very small inclusion(s)
Difficult to see with a 10X magnifying glass
SI1 SI2 : Small inclusion(s)
Easy to see with a 10X magnifying glass and difficult to see with naked eye
P1 P2 P3 : Included
Easy to see with naked eye
Diamond cut
When a diamond is well cut, light reflects from one facet to the other, making the most of the diamond's high refractive property. A less well-cut diamond lets some of the light escape.
Our recommandation
We advise you to choose a diamond with a quality rating equal to Excellent (EX) or Very Good (VG) to maximize the refraction of light and therefore the diamond brilliance.
EXExcellent
VGVery Good
GGood
FFair
PPoor
Most recognized certificates: GIA, HRD and IGI
Always ask to see the certificate before purchasing a certified diamond. For all of our certified diamonds, we display a link (GIA, HRD or IGI) that you can click to view the diamond’s full certificate.
We only offer natural diamonds accompanied by a certificate of authenticity and quality issued by one of the 3 most prestigious and world-renowned laboratories: GIA, HRD and IGI. The certificate number is engraved on the girdle (circumference) of all our HRD, IGI and GIA certified diamonds.
Laser engraving
The three major diamond certification laboratories HRD, IGI and GIA laser engrave the certificate number on the girdle (circumference) of the diamond. The certificate number is therefore engraved on all our HRD, IGI and GIA certified diamonds. This is a proof of the good match of the diamond and its certificate. The inscription is very small (to preserve the purity of the stone) and very difficult to read with the magnifying glass 10X.
If you order only the diamond (without the jewel), it will be delivered under seal in a rigid plastic pouch (see photo below) for diamonds certified by HRD or by IGI. For GIA diamonds, the seal must be specifically requested in the comments field during the ordering process.
Diamond Fluorescence
Fluorescence is a luminous effect that some diamonds exhibit when exposed to ultraviolet light. They show visible light, usually blue.
Our recommandation
Since fluorescence may in some cases give a milky diamond appearance, prefer a diamond without fluorescence ("None" or "Nil")
None or Nil
Absence of fluorescence
Slight or Faint
Little fluorescence
Medium
Medium fluorescence
Strong
Strong fluorescence
Very Strong
Very strong fluorescence
Diamond Polishing
When cutting the diamond, each facet must be polished. If a diamond has no scratches or very minor scratches on the surface, the polish is high. The better the polishing, the more it allows the transmission of light through the different facets of the diamond.
Our recommandation
We recommend choosing a polish rated Excellent (EX) or Very Good (VG) to ensure the best finish and shine.
EXExcellent
VGVery Good
GGood
FFair
PPoor
Diamond Symmetry
Symmetry describes the symmetrical accuracy of the facets of the diamond in terms of dimensions and angles, as well as the centering of the table and the centering of the breech point of the diamond. A higher level of symmetry creates optimal shine and scintillation.
Our recommandation
We advise you to choose a diamond with a symmetry rating equal to Excellent (EX) or Very Good (VG) to maximize the sparkle.
EXExcellent
VGVery Good
GGood
FFair
PPoor
