FL and IF diamonds are next to each other on the Clarity scale, with FL being the highest grading. When FL and IF diamonds are viewed under 10x magnification, no imperfections are noticeable.
The biggest difference is that unlike flawless diamonds, internally flawless diamonds have slight surface blemishes. An IF diamond, for instance, might have surface graining, extra facets or minor polish marks.
Without the help of magnification and a professional gemologist’s eye, no one can tell the difference between FL and IF diamonds. Even trained professionals can have a difficult time distinguishing the two.