Where the trade buys and sells in person: gem markets, trading districts, diamond exchanges and gem towns, with what is traded and when to go.
Trading district
Antwerp, Belgium
Traded: Rough and polished diamonds
About a square mile beside Antwerp Central station, through which most of the world's rough diamonds pass. The car-free Hoveniersstraat, Rijfstraat and Schupstraat form its core; its four diamond bourses are open to vetted members.
Gem town
Idar-Oberstein, Germany
Traded: Coloured stones and agate: cutting, carving and trading
Gem town on the Nahe river where agate cutting began in the late Middle Ages. It now cuts and trades coloured stones from around the world, and is home to the German Gemmological Association and the German Gem Museum.
Places, not businesses: JewelLoop does not rank, recommend or endorse any dealer. Days and hours change, so check locally before you travel. Street markets also sell imitations, synthetics and undisclosed treatments: buy important stones with a report from a recognised laboratory, and follow the export and customs rules of every country involved.