Tourbillon

A tourbillon is a mechanism that mounts the balance and escapement in a rotating cage, originally intended to average out timing errors caused by gravity when a watch is held in different positions.

Today it's mainly a showcase of craftsmanship, and tourbillon watches are typically expensive and specialised. Servicing is complex and should go to a qualified specialist.

Tourbillon watches are a narrow market, so check liquidity carefully and price conservatively unless you know the buyers for them.

Because they're often sold through specialist channels, check how long comparable pieces have taken to sell before committing capital to one.