4Cs of Diamond
The 4Cs of Diamond Quality are the universal method for assessing the quality of any diamond worldwide. This grading standard was created by the Gemological Institute of America (GIA).
Gemmologists and diamond experts use established scientific methods to measure a stone's colour, internal purity, geometric precision, and physical weight to evaluate and grade diamonds. Thanks to this global standard, customers are able to understand a diamond’s quality, value and price.
Each C in the 4C framework stands for a particular criterion or parameter. The 4Cs are Colour, Clarity, Cut and Carat Weight.
Colour: Colour is graded from D (completely Colourless) to Z (light yellow or brown).
Clarity: Clarity evaluates the internal purity of a diamond and is graded from Flawless (FL) to Included (I3).
Cut: Cut measures how precisely a diamond's facets are engineered and angled to reflect light and is graded from Excellent to Poor.
Carat: Carat refers to the physical weight of the diamond and is measured in carats (1 carat equals 2000 milligrams.
Diamond Colour
The colour of a diamond is graded by how colourless it is. Diamond colour refers to the absence of colour.
The colour of a diamond varies from colourless to light yellow, and the GIA colour grading scale ranges from D to Z.
D to F: Colourless
G to J: Near Colourless
K to M: Faint Yellow
N to R: Very Light Yellow
S to Z: Light Yellow
The D-coloured diamond is the most colourless diamond, while a Z-coloured diamond contains a noticeable brown or yellow tint. This is why D coloured diamonds are the most prized and valuable.
Fancy colour diamonds are diamonds with colour that extends beyond the Z range. They are rarer compared to regular diamonds. In the world of fancy-coloured diamonds rarity dictates market value. Yellows and browns are readily available, tones like pink and blue are highly sought after, and red, green, purple, and orange are the ultimate collectors' items. Here colour intensity overrides clarity; a diamond displaying exceptional hue remains highly valuable to collectors even with a lower clarity grade.
Diamond Clarity
Diamond Clarity measures a diamond’s purity, and it refers to the absence of inclusions and blemishes. Clarity grades are given depending on the number, size, nature, and position of blemishes and inclusions, and also how these affect the overall appearance and beauty of the diamond.
Diamonds are graded by examining them under 10x magnification using a "loupe" or a microscope. A diamond with no inclusions visible to the naked eye is called an “eye-clean”.
The GIA Clarity Scale features 11 distinct grades divided into 6 main categories:
Flawless (FL): No inclusions or blemishes visible under 10x magnification. These are incredibly rare and highly prized.
Internally Flawless (IF): No internal inclusions, with only minor surface blemishes visible under magnification.
Very, Very Slightly Included (VVS1 and VVS2): Inclusions are so microscopic that they are extremely difficult for even a skilled gemmologist to see under 10x magnification.
Very Slightly Included (VS1 and VS2): Minor inclusions that are clearly visible under magnification but typically invisible to the naked eye ("eye-clean").
Slightly Included (SI1 and SI2): Inclusions are easily noticeable under 10x magnification and may sometimes be visible to the unaided eye upon close inspection.
Included (I1, I2, and I3): Inclusions are obvious under 10x magnification and are clearly visible to the naked eye. These can affect the diamond's overall brilliance and structural durability.
For most jewellery buyers, the VS and VVS categories represent the absolute sweet spot, offering flawless visual beauty to the naked eye without the extreme price premium of a completely Flawless diamond.
Diamond Cut
Diamond cut means how well a diamond’s facets interact with light to create desirable visual effects. Of all the diamond 4Cs, Diamond cut is the most complex and technically difficult to analyse and grade.
The description of the Cut Grade on a grading report is subdivided into:
Cut grade, polish, and symmetry.
Each of these are graded into 4 categories:
Excellent, Very Good, Good, and Fair.
Cut grade: In Cut grade, the proportions of the facets of a round diamond are evaluated for ‘brightness’, ‘fire’ and ‘scintillation’. Cut grades are only given to round diamonds and not to "fancy shapes" (shapes other than round, like oval, cushion, etc.)
Polish: In polish, the quality of polish on the diamond facets is checked.
Symmetry: In symmetry, the diamond is graded based on how precisely the various facets of a diamond align and intersect.
Diamond Carat
Carat is the unit of measurement for the weight of diamonds. 1 carat (ct) is equal to 0.200 grams and 1 carat is divided into 100 cents.
10 carat is written as 10.00 ct, and 10 carat and 75 cents is written as 10.75 ct.
0.10 carat is also referred to as ‘10 cents’ or ‘10 pointer’, 0.50 carats as a ‘50 pointer’ or ‘half carat’, 1.00 carats as ‘one carat’.
The weight of a diamond is the most visible indicator of a diamond's overall size and presence, and the most significant factor affecting its price.