Is 9 mm round cut moissanite equivalent to a 3 carat?

A 9 mm round cut moissanite is approximately equivalent to a 3 carat diamond in size. However, due to the different densities and refractive properties of moissanite compared to diamond, a moissanite may appear larger than a diamond of the same carat weight. Therefore, while the size is similar, the visual impact can differ.