FL
FL (Flawless) diamonds exhibit exceptional clarity, with no internal or external inclusions visible under 10× magnification. They represent the highest grade on the GIA (Gemological Institute of America) clarity scale and are extremely rare — both in nature and among lab-grown diamonds.
In laboratory environments, FL diamonds are produced using HPHT (High Pressure High Temperature) or CVD (Chemical Vapor Deposition) technologies, sometimes followed by thermal treatment (annealing). Annealing is used to enhance visual appeal by subtly improving a diamond’s color or clarity.