Diamond 4Cs: Loose Diamonds Education

Explaining Clarity Grades: Beyond The Letters and Numbers

 

Based on seminar given by Diane Flora, CGA, here is an overview of the grading techniques used by the GIA to determine the clarity grade for loose diamonds. During the seminar, Diane Flora explained the 5 factors that are used: relief, position, nature, number and size. Each factor is equally important but play a different role in the a specific diamond's clarity grade and ultimately the diamond price.

Let's take a look at each of the 5 factors:

  • Relief: Depending on the color of the inclusion, it can stand out in high relief against the reflections within the diamond. For example, in a colorless diamond a blackish imperfection will be much more apparent than if the inclusion were white.
  • Position:Some inclusions are positioned on the side of the diamond, near the edge of the table, but sometimes the imperfection will be right in the center of the table of the diamond making it stand out much more. The position of the imperfection determines its visibility and therefore plays a role in the diamond clarity grade.
  • Nature:There are different types of imperfections, either internally as inclusions or externally as blemishes. Depending on the type of inclusion, it can be called a crystal or a feather.
  • Number:The amount of inclusions or blemishes is part of the diamond clarity grade. Even if there is a single crystal as an inclusion, if its position causes it to reflect multiple times within the diamond, it is counted as several inclusions.
  • Size: This does not refer to the size of the diamond like 1 carat diamond ring, but rather the size of inclusion in relation to the actual size of the loose diamond. That relation plays a role in determining the total price of the diamond. The same size inclusion has different impact in a 4 carat diamond compared to a 1 carat diamond for example.

 

What clarity grades means for you when picking a diamond

 

When you're looking at different loose diamonds, make sure to evaluate the clarity by looking at the five factors. The first check is to see if the imperfections are eye-visible. If an inclusion is eye-visible it does not automatically mean a stone is graded "Included".

When a diamond is graded as Internally Flawless, it will no inclusions at all. If a pinpoint is visible through the pavilion, the diamond usually receives a VVS1 diamond clarity grading, unless the pinpoint is visible through the crowns, in which case it would receive a VVS2 grading. When an inclusion is larger, the clarity grade can typically go no higher than VS1. Below VS1, it becomes harder to predict the clarity grade as the varying combinations of the 5 factors determine the grade.

The GIA clarity grading process

Wet grading is the technique used by GIA graders. They use a wet sponge or brush with a little soap to wipe the surface of the diamond to remove dust and surface reflections. Soap is used to prevent water from collecting on the diamond in the form of beads, which would distort the image. After the initial face-up impression of the diamond, grades will then check the condition of the culet by looking through the table. If the culet is chipped, the diamond will not be graded as Internally Flawless because chipping is considered a form of imperfection.

Then the stone is "divided" into 8 sections, each containing a part of the pavilion, girdle, bezel, star facet and two lower girdle facets. Each of these sections is examined by the GIA diamond grader under high magnification to find any inclusions. The diamond is then observed face up under 10x magnification under lab conditioning lighting. Any visible inclusions are identified, mostly for their position. In the end, a final unaided eye check is done to determine the condition of the clarity under normal circumstances. For example, does that little inclusion on the side make the 2 carat diamond ring you love look less sparkling Only then, after the process is finished, will the GIA diamond grader determine the clarity grade. The detailed results of the grading are stated in the GIA diamond grading report to show how each of the 5 factors have been assessed.

Now that you know the process of the professionals, you should be well-equipped to take an analytical and critical look at the diamond clarity of the loose diamonds you are considering to buy. These factors carry the same importance across different diamond shapes, so whether you're looking for a princess cut engagement ring or cushion cut engagement ring, you know exactly what to look for and what makes them sparkle.