A jeweler can identify a lab-grown diamond just by looking.

Lab-grown and mined diamonds are atomically identical and have the identical optical properties that make diamonds sparkle.

A jeweler’s eyes can assess a stone’s appearance and quality but that is different from telling its atomic structure and how it formed.

GIA says traditional observations and instruments are not enough to distinguish many laboratory-grown diamonds from mined ones and advanced testing may be needed.

Specialized laboratory testing can distinguish lab-grown from mined diamonds. A polished diamond’s mining country cannot be established by examining the stone alone; documented provenance is needed.