The short answer
If you searched for "counterfeit 5105," you probably have a watch with 5105 stamped on the case back or printed somewhere on the movement, and you want to know whether it is real. That number alone tells you almost nothing. On watches, 5105 turns up as a case reference in some catalogs and as a caliber number on some movements, and counterfeiters copy both markings without much trouble. Treat the number as a starting point, not a verdict. What separates genuine from fake is the finish of the parts, the consistency of the engraving, and whether the paperwork and the asking price make sense together.
What 5105 usually refers to
Case references and caliber numbers live in different places, and people mix them up constantly. A case reference is tied to a specific model line, case size, and dial variant, so the same brand can have many watches that share a movement but not a case number. A caliber number describes the engine inside and may appear in dozens of different models. Before you judge a watch, figure out which one you are looking at. Check the inside of the case back, the rotor, and the bridge stamping. If the number on the movement does not match the number pattern the brand uses for that era, that mismatch is your first clue.
The checks I run first
- Look at the engraving under magnification. Genuine stamps are cut or laser-etched with clean edges and even depth. Fake stamps look shallow, fuzzy, or too heavy.
- Compare fonts against reference photos from the brand's own catalog or a dealer's listing for the same reference and year.
- Weigh the watch. Counterfeit cases are often plated brass or lower-grade steel, and the difference shows on a scale.
- Check the crown action and the winding feel. A gritty or loose crown on a watch sold as new is a bad sign.
- Look at the dial printing and the hands. Uneven lume, misaligned markers, or hands that are flat instead of faceted show up on almost every fake.
The movement is where fakes fall apart
Case finishing can be copied well enough to fool a photo. Movements are harder. Pull the case back, or ask a watchmaker to do it, and look at the finishing on the bridges and rotor. Real movements show Geneva stripes with crisp edges, polished screws, and jewels set flush in clean chatons. Cheap copies show stamped patterns that fade at the edges, screws with tool marks, and a rotor that wobbles. If someone refuses to let a watchmaker open the case before you buy, that refusal is the answer.
Price and paperwork together
A price far below market for the reference is the oldest signal there is, and it still works. Counterfeiters rely on buyers who want the deal more than they want the proof. Paperwork deserves the same suspicion. Boxes, warranty cards, and manuals are printed in bulk and sold separately, so a full set proves less than most people assume. Check that the serial on the card matches the serial on the case, and call the brand or an authorized dealer to confirm the reference exists as described. A watch that the brand cannot identify is not a bargain.
Red flags in online listings
- Stock photos instead of pictures of the actual watch, especially of the case back and movement.
- Sellers who use the words replica, homage, and genuine in the same listing.
- Prices that sit 60 percent or more below the going rate for that reference.
- No return window, or a return policy that only applies if the watch is unopened.
- Pressure to pay outside a platform with buyer protection.
If you already bought one
Document everything before you confront the seller: photos of the watch, the listing, the payment record, and any messages. Contact your card issuer or payment platform about a chargeback, since counterfeit goods are usually covered. Customs agencies in most countries seize counterfeit watches routinely and publish guidance on what happens next, so report the seller if the purchase crossed a border. Then take the watch to an independent watchmaker for a written opinion. That document is what turns a suspicion into a case.