What does symmetry mean for a lab-grown diamond?

Symmetry is a cut-quality grade that measures how precisely a diamond's facets align with one another and meet at the girdle. IGI grades symmetry on a scale from Ideal to Poor, with Excellent and Very Good being the most common grades in well-cut lab-grown diamonds. Minor deviations, such as a slightly off-center culet or facets that don't converge cleanly at the girdle, are invisible without magnification and have negligible impact on appearance. Where symmetry matters most is in fancy shapes: a lab-grown heart, for instance, requires near-perfect bilateral balance, so an Excellent symmetry grade becomes a practical requirement rather than a premium add-on. For round brilliants, an Excellent or Very Good grade is sufficient for most buyers.