Grading Clarity (6.15)
Holding the diamond directly under your light source, look through the top (crown) of the diamond with your 10x loupe, making mental notes of your first impressions. Divide the diamond into imaginary sections and carefully examine the stone from each surface area, going deeper into the stone by readjusting the stone’s distance to your new focal level. Identify the reflection of the tweezers in the stone and familiarize yourself with it to avoid confusion.
Rotate the tweezers to view through the back (or pavilion) and make mental notes of inclusions or blemishes that were not visible from the crown. After thorough examination through the pavilion, turn the tweezers back to the crown and looking through the crown, try to locate the same inclusions that you saw from the pavilion side. It is often easier to locate inclusions through the pavilion that might otherwise be difficult to see through the crown, due to the interference of brilliance and dispersion in the stone. Many times, smaller inclusions or blemishes are simply overlooked due to carelessness. More than likely, the inclusion you missed looking through the crown you will detect through the pavilion. It is also advised to rotate the diamond to view the area in which the tongs or tweezers contacted the subject previously. The two main rules of clarity grading are: The final grade is based on what you see under 10x magnification. Only the inclusions detected through the crown are allowed toward the final grade.
Again it is acceptable to zoom a scope’s power to high magnification to aid in locating inclusions and blemishes, but then you must reduce the magnification to 10x to set the final grade. Viewing through the pavilion of the diamond is not only acceptable but mandatory, for accurate and professional clarity grading.