This refers to the presence of inclusions in a diamond. Inclusions are natural identifying characteristics such as minerals or fractures, that appear while diamonds are being formed. They may look like tiny crystals, clouds or feathers. Inclusions are usually viewed at 10x magnification.
The position of inclusions can greatly affect the value of a diamond. Some inclusions can be hidden by a mounting, thus having little effect on the beauty of a diamond. An inclusion in the middle or top of a diamond could impact the dispersion of light, making the diamond less brilliant. Inclusions are ranked on a scale of perfection known as the clarity scale. The scale ranges from F (Flawless) to I (Included) and is based on the visibility of inclusions at 10X magnification. In addition each basic grade is followed by the number 1,2 or 3 to indicates the severity of the inclusion(s).
The basic rule of thumb is if you can see the inclusion(s) with your naked eye then it is an “I” grade stone. If you can’t see an inclusion with your naked eye it is either an IF, VS or SI grade stone (AKA – eye clean) & will need to be viewed with 10x magnification loupe to further determine the grade. If you can easily see it with a 10x loupe then it falls somewhere into the SI grade & if a 10x magnification doesn’t show the inclusion then you’ll need further magnification to narrow the grade to VS or IF.