What are facets on a diamond?

Facets are the flat, polished surfaces cut into a diamond's exterior to control how light enters, bends, and exits the stone. Each facet is ground using a rotating cast-iron disc coated with diamond powder, the only abrasive hard enough to shape diamond. A standard round brilliant carries 57 facets, a number refined over decades to maximize the interaction between light and the stone's internal geometry. In a lab-grown diamond, the atomic structure governs light behaviour exactly as it does in any diamond, so facet precision is what sets brilliance apart. What changes with facet count and precision is the balance between brilliance (white light return), fire (spectral colour dispersion), and scintillation (the flash pattern when the stone moves). IGI grading reports assess cut quality, which directly reflects facet precision. A well-cut lab-grown diamond with accurate facet angles will outperform a poorly cut stone of higher colour or clarity grade.