If authenticity matters to you, buying directly from Longchamp or from an authorised retailer is the simplest option. If you're shopping pre-owned, ask the seller for clear photographs of the logo, leather tab, stitching, hardware, interior label and any identifying markings before paying.

And if the seller refuses to provide basic photographs, rushes you into buying or gives vague answers about where the bag came from, it's probably better to walk away.

One detail rarely tells the whole story. A convincing fake may get the logo right but mess up the stitching, or copy the leather while getting the hardware wrong. Look at the bag as a whole, and don't let a tempting price make the decision for you.