When you speak of diamond clarity, you’re actually talking about the overall appearance and internal characteristics of the diamond, often referred to as inclusions. The defects on the surface are called blemishes. Among the 4 c’s of grading qualities, clarity marks as one of the most important ones, other than carat, colour and cut. Inclusions can mainly come from foreign materials naturally crystallized, or with structural imperfections which can certain portions whitish or clouded. The location, size, colour, orientation, number and visibility of these inclusions can affect the clarity and hence the grading of the diamond. Clarity grading is thereby assigned to stones based on visual appearance under magnification.
While many of the inclusions in diamonds and gems don’t affect its strength or integrity – large inclusions both in size and numbers, can alter the diamond’s ability to reflect and scatter light. Also large cracks on the surface are known to diminish a diamond’s strength greatly.
Diamonds with greater clarity grades are more expensive – the rare Flawless grade being the most sought after. Slight blemishes work like fingerprints and can help in identifying the unique characteristics of diamonds. Inclusions also help in identifying the subtle differences between natural and synthetically produced diamonds, as the technology creating synthetic diamonds are getting better with time.
Inclusions and blemishes
There can be a number of blemishes and inclusions which can affect the clarity of a given diamond. Laser lines and other diamond facet enhancement modules are also included in this list.
• Included crystals or minerals
• Internal graining
• Laser Lines
It is more common to hear the term “internal characteristics” instead of inclusions thrown around by the ones in the diamond industry. These “internal characteristics” refer to the growth crystals that lend a diamond its uniqueness. Diamonds are effectively graded under 10x magnification.
• Polish lines
• Grain boundaries
• Dark spots
Gemological Institute of America (GIA)
The year 1952, saw the coming together of Richard T Liddicoat, Marquis Person, Joe Phillips, Robert Crowningshield and Bert Krashes to commence working on what they called “diamond grading and evaluation appraisal”. Within a year, they developed a sound assessment based on the colour make and clarity of the diamond. Using the terms thrown around in the industry at the time, they coined their terminology and defined definitions for their methods. The existing system contained the following nine grades, with the latter two, being considered as “Imperfect” – Flawless, VVS1, VVS2, VS1, VS2, SI1, SI2, I1, and I2.
With the onset of the 1970’s a couple of changes were made. Firstly, the Internally Flawless grade came into being, as GIA observed the ruthless cutting of diamonds to remove blemishes on the surface thereby altering its overall make. With this grade, the diamond manufacturers could make the choice of leaving the blemishes on the surface and yet achieve a grade higher than VVS1. The I3 grade was the next to be included to grade a number of diamonds that had very low clarity.
The final change took place in the 1990s when the term “imperfect” was altered to “included”.
The Present GIA grading system
GIA diamond clarity grading scale
The GIA diamond grading scale has been divided into six categories with eleven grades. The clarity categories and grades are as follows:
• Flawless category (FL) diamonds do not have any inclusions or blemishes that are visible under 10x magnification.
• Internally Flawless category (IF) diamonds have no blemishes visible under 10x magnification, but ever so slight surface flaws on the diamond.
• Very, Very Slightly Included category (VVS) diamonds have such minute blemishes that it becomes difficult for a trained diamond grader to identify under 10x magnification. The VVS category is subdivided further into; VVS1 with a higher clarity grade than VVS2. The VVS category is set by pinpoints and needles.
• Very Slightly Included category (VS) diamonds contain minor inclusions that are somewhat easier for a trained grader to see under 10x magnification than the VVS category. The VS category is also subdivided into two grades – VS1 possesses a higher clarity grade than VS2. The blemishes in VS diamonds are practically invisible without magnification, but it isn’t uncommon for some VS2 inclusions may still be visible. A fitting example would be a small inclusion under the corner of the table of a large emerald cut diamond.
• Slightly Included category (SI) diamonds have noticeable blemishes that are relatively easy to spot when viewed under 10x magnification. The SI category is again further divided into two grades – SI1 has a higher clarity grade than SI2which might not appear obvious to the naked eye.
• Included category (I) diamonds have visible inclusions that a trained grader can easily identify under 10x magnification. Some of these inclusions are visible to the naked eye as well, which threaten to affect the durability of the stone. This category is further divided into three grades; with I1 possessing a higher clarity grade than I2, which in turn is higher than I3. I1 inclusions may often be invisible to the naked eye without further aid, as compared to the more easily viewed inclusions in I2 and large inclusions in I3, thereby impacting the brilliance and structure of the diamond.
GIA Clarity Grading Procedure
Grading according to the GIA standards is strictly performed under 10x magnification with darkfield illumination. The GIA Laboratory uses standard equipment including binocular stereo microscopes that can zoom to higher magnifications. These microscopes possess darkfield illumination mechanisms along with filtered UV light. Handheld loupes with 10x magnification make grading difficult as the proper lighting to illuminate the side of the base, without flooding the crown is absent.
After the diamond has been cleaned, it is picked up by tweezers using the girdle to girdle to hold. The first view is made through the table as the grader studies the culet area for blemishes and inclusions. It is then set down, and picked up again for a table to culet hold. This opens the pavilion side, and the crown side, for examination. After each sector examination, the diamond is carefully rotated in the tweezers so as to examine the next sections. Darkfield lighting reveal characteristics, and can be alternated to reflect all surfaces. Overhead lighting is used to make sure of a characteristic within the stone, surface, or both. A stereo microscope allows graders to zoom in to higher magnifications to closely observe inclusions, and eventually return to 10x magnification for final assessment and clarity grading to make an assessment of its impact on the clarity grade.
If cases where the use of a stereo binocular microscope cannot be ruled out, the final assessment is made using a 10x loupe to determine the clarity of the stone. The grades for the stone are then decided upon and categorized such – (FL, or IF for a blemish), minute (VVS), minor (VS), noticeable (SI), or obvious (I).