GIA Diamond Clarity Rating Procedure
According to the GIA standards, a diamond clarity rating is performed under the following circumstances: The stone is first thoroughly cleaned, and then the diamond is picked up by tweezers that hold the stone girdle-to-girdle. The diamond is placed under 10x magnification equipped with darkfield illumination. The darkfield lighting can be used to reveal characteristics that are not seen with the overhead lighting. The overhead light must filter ultraviolet light. If a grader is using a microscope with higher magnification, they may zoom in to get a closer view of the flaws, but the diamond clarity rating must be based off the 10x magnification power.
The first view of the diamond is through the table, the culet area of the stone is examined for any flaws. The diamond is then set down, and picked up with the tweezers holding the stone from table-to-culet. The diamond is then viewed from crown side and pavilion side, inspecting the stone through each facet looking for flaws. Once all of the facets have been viewed, the diamond is rotated in the tweezers so that the person can view the next area of facets.
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