How Clarity is graded

Vision varies from person to person. What one person can see with the unaided eye, another one can’t see. They same goes for examination under 10 power.
Most consumers think that graded under 10 X magnification means that the grader looked only at 10 X. This is not true. When examining a diamond the grader can increase the magnification until he finds all the inclusions. Once an inclusion is seen at whatever power, the grader then looks for that inclusion at 10x to see if it can still be observed. If so, the inclusion is considered when determining a clarity grading.
The stone is examined in a multitude of positions. Clarity grading is determined only in the face up position.
In order to properly examine a diamond’s clarity, it is necessary to examine it using dark field illumination. Looking at a diamond without dark field illumination is invalid as some inclusions might not be visible, and thus not an accurate method of clarity grading.
Before we determine the description of each clarity grade, readers should be aware that the major labs ( GIA, AGS etc.) are more “forgiving” in assigning clarity grades for stone that weigh more than 1.50 carats.
Diamonds that are step cut , such as the Emerald Cut or Asscher will show inclusions easier than rounds or stones with other styles of pavilion (underside) faceting.
Standards of Clarity Grading
The standards listed below are for GIA grading ONLY. Some labs such as IGI and EGL have different standards. It is the author’s opinion that unless the GIA standards are adhered to, the consumer assumes that an EGL SI-2 stone is equal to an SI-2 clarity graded stone from GIA.
What makes this more confusing for consumer’s is that all the labs use the GIA nomenclature, even when their standards are different. It is the author’s opinion that if a lab doesn’t adhere to the standards of GIA, the terminology should be different. However, it isn’t.
For example IGI and EGL use the grade of SI-3. If GIA were to grade a stone graded SI-3 – the result would usually be equal to I-1 in GIA terminology. However, SI-3 was “invented” by these labs, for stones that would be borderline I-1’s.
Preferred Types of Inclusions
The smallest inclusions are the most preferred.
Small inclusions would be
Pinpoints
Needles
Clouds ( clusters or groups of pinpoints)
Wisps
Other inclusions:
Crystals (transparent ones face up)
Feathers - (but not where they are opening on surface of the diamond or at the girdle of the stone) Size also matters too, as well as location in the stone.
Least Preferred Inclusions
Cleavages – These are cracks in the stone which run parallel to the grain of the diamond.
Eye Clean – What does it REALLY mean?
Generally, the clarity grades of VS are usually eye clean. Eye clean means that the diamond does not have visible inclusions to the unaided eye, examined in proper lights, held with the table of the diamond perpendicular to the eye (face up) and a distance of approximately 12-15 inches.
VVS1 & VVS2 CLARITY GRADES
The terms VVS-1, very very small 1, and VVS-2, very very small 2, describe diamonds that when viewed under 10X magnification by an expert show only very, very small inclusions which are difficult to be seen. The inclusions should be light colored. The features of the VVS grade are exceptionally difficult to discern. The typical inclusions of this grade are dot-like inclusions. Whether a diamond is VVS-1 or VVS-2 depends on the relative degree to which the minute inclusions are present. If they are present to a minimal degree then the VVS-1 grade is chosen. Just a little added touch to the degree of inclusions will result in a VVS-2 grade.
VS1 & VS2 CLAITY GRADES
Diamonds are classified into the VS, very small inclusions grade, when the expert using a ten times magnification can discern very small inclusions which are difficult to be seen. The experienced grader does not find the internal faults at once, but does not have too great difficulties to see the inclusions when he moves the diamond a little from side to side. Typical inclusions of this group are small, light clouds or small light cracks on the girdle as well as single crystals just slightly larger than a dot. Inclusions in this clarity grade should be mainly light-colored. Very small dark inclusions are allowable under the girdle. Depending on the degree of inclusions the diamond is either rated VS-1 having fewer inclusions or VS-2 having just a little higher degree of inclusions.
SI1 & SI2 CLARITY GRADES
The SI or 'small inclusions' term comprises diamonds which, when viewed with ten times magnification have small inclusions. These are usually easily seen by an experienced grader. As soon as he observes the diamond with the right magnification the inclusions jump into the field of view and should be light and around the girdle there can be small, dark inclusions. Again, depending on the degree to which inclusions are present the diamond is either rated SI-1 or SI-2, with the SI-1 having a lesser degree of inclusions than an SI-2.
I-1 – I-2 OR (IMPERFECT) CLARITY GRADES
The I-1 (Imperfect-1) grade sometimes is referred to as the P-1 or (Pique'-1) grade. The word pique' is a French word meaning 'mark' or 'spot'. The I-1 grade comprises those diamonds which when viewed with ten times magnification show several inclusions at once but which do not diminish the brilliance. With the naked eye, when viewed through the crown, these faults, even in larger diamonds, are only discernible with difficulty. Typical defects of this group are larger colored inclusions as well as larger cracks or plane-like inclusions. The I-2 (Imperfect-2) or P-2 grade is comprised of diamonds with larger and/ or numerous inclusions which can be seen with the naked eye through the crown and which may diminish the brilliance somewhat even in smaller diamonds. There might be dark inclusions or numerous light-colored features. Another characteristic is larger cracks which may influence the durability of the stone and they could possibly expand under stress into the interior of the diamond, especially if they are to be found near the girdle.
It is not recommended to purchase a diamond with a clarity grade of I-2 or lower since the multitude of inclusions will tend to block or impede the passage of light through the diamond and thus reduce the overall brilliancy. Also, the presence of larger inclusions especially cleavage-like inclusions will create a certain amount of internal strain that will ultimately weaken the diamond.
However, there are to be found large diamonds with an I-2 clarity that seem to be quite brilliant and are quite strong. Ask your independent gemologist his opinion on any I-2 or lower clarity diamond. Ask him specifically about reduced brilliancy and the overall strength of the diamond.
I-3 CLARITY GRADE
The I-3 (Imperfect-3) or P-3( Pique'-3) clarity grade is the lowest grade of clarity and is comprised of large and/ or numerous inclusions which are easily visible through the crown with the naked eye. The number and size of inclusions usually diminish the brilliance considerably.