The Diamond 4Cs are the following: Colour, Clarity, Cut and Carat Weight.
The 4Cs – Colour
Colour grades evaluate the body colour- or lack thereof- of a diamond. Although usually presented as a ‘white’ or colourless gemstone (barring ‘fancy’ coloured diamonds- see below colour grades), most diamonds show tones of yellows, browns and grays, ranging from extremely faint to dark. Colour is graded using a daylight equivalent grading light using the letters of the alphabet from D through Z. A diamond grader usually employs a pre-graded master set of diamonds to ensure consistency between very subtle grades.
D is the top colour grade in ‘white’ diamonds. It indicates that the stone appears truly colourless under a daylight equivalent grading light. D colour diamonds are often described as displaying a very cool, ‘icy’ tone due to their absolute lack of colour.
E – F
E and F grades are still top grades and regarded as colourless. The difference in tone from D through F essentially requires a skilled grader and an ideal grading environment to be perceived.
G – H
Still appearing mainly colourless, G and H stones feature a very light yellow or brownish body colour, detectable under daytime equivalent grading light.
I – J
At I and J, the light yellow or brown tones are more readily detectable, both under the grading light and regular/incandescent light, especially in loose stones or stones set in white metal.
K – L – M
The stone’s body colour becomes more obvious as yellow or brown, under various lightings and to the untrained eye.
N to Z
From N through Z, the stone’s body colour is obviously yellowish or brownish, the shades getting darker as the grades move towards the bottom of the scale.
Fancy Coloured Diamonds
Natural ‘fancy’ coloured diamonds include shades of yellow and brown that are more vibrant than the tones included within the D – Z system. As with other unusual diamond colours like blue, pink, violet and the very rare greens and reds, fancy yellows and browns are regarded as highly attractive and graded using a special system that describes the stone’s colour and strength with qualifiers such as Faint, Light, Intense and Vivid.
Artificially coloured diamonds are not graded for colour.
The 4Cs – Clarity
Clarity grades determine the visual impact (and effect on durability) of a diamonds internal characteristics (inclusions) and surface blemishes. Common inclusions and blemishes include- but are not limited to- internal crystals (often referred to as ‘carbon spots’ although they are most often small internal diamond crystals or other minerals, like garnet), internal fractures (called ‘feathers’, harmless to the stone if small), knots within the crystal lattice, graining (line patterns from crystal growth), holes small or large on the surface (called ‘pits’ or ‘cavities’), scratches and cutting features like extra facets or polishing marks.
Each clarity grade takes in consideration the size, number, nature, position, relief and colour of the diamond’s characteristics under 10X magnification.
F – Flawless
F grade is relatively rare and indicates that there are no inclusions or blemishes visible under 10X magnification.
IF – Internally Flawless
IF grade allows for minor external blemishes, like a tiny extra facet or very small/faint scratches, but no internal characteristics (under 10X magnification).
VVS1 – VVS2
VVS indicates that very minute characteristics are visible to a skilled grader, again under 10X magnification. The difference between 1 and 2 express how discrete these characteristics appear to the grader within the VVS range.
VS1 – VS2
VS grade features characteristics that are minor under 10x magnification but somewhat easy to locate by a skilled grader. Again, the difference between VS1 and 2 is determined by how easily these minor characteristics are located by the grader.
SI1 grade indicates that while 10X magnification is still required to locate inclusions/blemishes, they are now fairly obvious to a grader. However they do not affect the stone’s brilliance, appearance or durability. The drop in price that occurs between the top grades and the SI grades reflect the rarity of those top grades rather than beauty and durability.
SI2 generally still requires 10X magnification to locate characteristics, however some features might be visible to the naked/untrained eye in larger stones. The SI2 stone should still appear mostly clean to the naked eye.
I1 grade usually features characteristics that are visible to the naked/untrained eye, such as a large internal crystal, a larger feather or visible graining. The I1 stone should still have mostly clean areas and have no characteristics compromising the stone’s durability.
I2 grade features numerous, large characteristics that are obvious to the naked/untrained eye. This is the threshold where the inclusions are large enough to increase a stone’s likeliness to crack, chip or break. Light may also be obstructed, reducing brilliance.
I3 indicates that large, obvious and numerous characteristics strongly affect the stone’s brilliance and appearance and that durability is heavily compromised.
Diamond Grading – Colour
The 4Cs – Cut
information to come…
The 4Cs – Carat Weight
information to come…