Lab-grown diamonds are certified and graded in the same way as natural diamonds. The most important factors are the 4 Cs: carat, cut, colour, and clarity.
Carat weight is the size of the diamond. The cut is the diamond’s symmetry, proportions, and polish. The colour is judged on a scale from D (no hue) to Z (a yellow hued diamond). Clarity is judged on a scale from IF (internally flawless) to I3 (included). Lab-grown diamonds can be certified by any of the major diamond grading laboratories, such as the GIA, IGI, or AGS.