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The 4 Cs

Cut, colour, clarity and carats - a guide to diamonds

The global standard for assessing diamonds was created by the Gemmological Institute of America (GIA) and comprises the 'Four Cs' - Colour, Clarity, Cut and Carat (weight).  By measuring each of these aspects, buyers and sellers can understand the quality of the diamond they are buying or selling!

 

Colour

The colour of a diamond is actually measured by the lack of colour - or the stone being 'colourless.'  This grading system ranges from 'D' which has no colour, to 'Z' which has light colour.  The GIA colour chart spells it out:

Diamond colour chart

Clarity

Clarity describes the absence of blemishes or inclusions and hte scale starts at 'flawless' and ends at 'included.'  The GIA clarity scale helps identify the level of clarity of your diamond:

Diamond clarity chart

 

 

FL

Flawless: No inclusions or blemishes are visible to a skilled grader using 10x magnification.

Extremely rare, less than 1 in 5000 jewellery quality diamonds are rated FL.

IF

Internally Flawless: No inclusions, only blemishes are visible to a skilled grader using 10x magnification.

FL and IF diamonds appear identical unless viewed under 10x magnification by a skilled grader. Less than 3% of jewellery quality diamonds are rated IF.

VVS1
VVS2

Very, Very Slightly Included: Inclusions are difficult for a skilled grader to see under 10x magnification.

VVS1 inclusions are typically only visible from the pavilion, while VVS2 inclusions are visible from the crown. In each, the inclusions are invisible to the eye, appearing identical to the higher grades unless viewed under 10x magnification by a skilled grader.

VS1
VS2

Very Slightly Included: Inclusions are clearly visible under 10x magnification but can be characterized as minor.

Inclusions are not visible to the naked eye. Perhaps 1 in 100 untrained observers can detect VS2 inclusions with the naked eye, on close inspection under ideal conditions.

SI1
SI2

Slightly Included: Inclusions are noticeable to a skilled grader using 10x magnification.

SI1 is the lowest grade with flaws often invisible to the naked eye. SI2 inclusions are usually visible to the naked eye, although they will require close inspection.

I1
I2
I3

Included: Inclusions are obvious under 10x magnification and may affect transparency and brilliance.

 I1-I3 diamonds have inclusions that are visible to the naked eye.

 

 

Cut

The cut allows light to interact with the diamond, which means the more workmanship that goes into the polish and cut, the better the 'sparkle.'  'Excellent' is ideal, which allows light to enter through the crown, refract, and exit again as that 'sparkle' you want.  Too shallow or too deep, and the cut really impacts on the quality and the price.

Diamond cut chart

 

Carat

The weight of a diamond is measured in carats, with 200 milligrams being equal to one carat. This is then divided into 100 points to allow a very precise measurement to the 100th decimal place. 

The value of a diamond is determined by taking into account every one of the 4 C's.  A ring's value is made up of the worth of the diamond, and market prices for whatever it is set in, such as platinum, gold, white gold, or silver.