Can a jeweller identify gemstones?

A qualified jeweller, with proper gemmological training, can generally spot most gemstones with the usual testing gear. But a retail jeweller without training cannot really nail down tricky synthetics or newer, upgraded treatments, unless they have specialised lab instruments on hand.

Simple checks, like telling a sapphire from plain glass or a diamond from cubic zirconia, are often achievable in the shop using a microscope, refractometer, and a polariscope setup. Still, today’s gem trade is filled with really convincing lab-grown stones and advanced treatments, and those need more advanced spectroscopy work. So when the stakes are high, a careful jeweller will commonly route the stone to a well-known independent gemmological laboratory first.