A stamped number such as 11 45100 on the back of a replica Audemars Piguet is a catalog clue, not a certificate. Use the code to identify which genuine reference the build copies, then judge the watch on measurable specs: case diameter, case thickness, movement beat rate, crystal material, bracelet construction, and finishing quality. No serial, case number, or Swiss made stamp on a counterfeit confirms origin, and counterfeit watches are illegal to sell in the United States, with shipments subject to seizure. Understand what you are comparing before any money changes hands.
What the 11 45100 Style Code Means
Audemars Piguet uses two separate number systems. Public references such as 5402, 14790, 15202, and 15500 identify models in the brand catalog. Case numbers and movement numbers are stamped inside or on the back of the watch and connect to service records held by the manufacturer. A string like 11 45100 reads like one of those internal case or batch numbers.
On a genuine watch, that number ties to a single production record. On a replica, the factory either copies a real stamp or invents a plausible one, then repeats it across an entire production run. Two replicas bought months apart can carry identical digits, which is the clearest sign the code carries no individual meaning.
What to Look For
Treat any code as the start of a comparison, not the end of one. The parts that decide whether a build looks convincing on the wrist are physical and countable:
- Case profile: does the octagonal bezel sit flush, and are the case flanks the right height and angle
- Dial texture: petit tapisserie squares should be crisp and evenly spaced, not soft or uneven
- Date wheel: font weight, position, and alignment inside the aperture
- Hands and markers: beveled edges, polished facets, and clean lume fill
- Crystal: sapphire with anti reflective coating on both faces, not mineral glass
- Bracelet: taper along the links, brushing direction, and how the clasp closes
- Caseback engraving: depth of cut and font consistency across every line
- Macro photos from the seller: if none exist, you are guessing
Parameter Bands Worth Checking
These ranges separate a careful build from a cheap one. Numbers outside the band are a warning, not a bargain.
- Case diameter: 37 mm to 42 mm for Royal Oak style cases, with 41 mm the most common
- Case thickness: genuine ultra thin models run 8 mm to 9 mm, replicas often 9.5 mm to 11.5 mm
- Movement beat rate: 28,800 vph (4 Hz) on the better clone calibers, 21,600 vph on cheap ones
- Power reserve: 38 to 60 hours, tested rather than quoted
- Steel grade: 316L is normal, 904L is claimed often and confirmed rarely
- Water resistance: assume splash resistance only unless a tester result is shown
- Weight: 120 g to 180 g depending on size and bracelet, which should feel dense for its volume
Common Pitfalls
- Paying extra for a 1:1 Swiss label that no seller can document
- Trusting a code that appears on hundreds of listings
- Ignoring thickness, the single easiest tell on an ultra thin design
- Buying from a listing with stock photos instead of macro shots of the actual unit
- Assuming gold plating will hold its color beyond a few months of daily wear
- Forgetting that customs officers can seize counterfeit shipments and that resale is not legal
FAQ
Does a matching code prove a watch is genuine?
No. Genuine authentication runs through the manufacturer service records, and replicas copy stamps with ease.
Why do so many replicas carry the same number?
Factories reuse one stamp across a production run instead of assigning individual numbers.
Is 11 45100 a real Audemars Piguet reference?
Public reference numbers follow a different pattern, so treat the string as an internal case stamp and verify the model against the official catalog.
What should I inspect first on arrival?
Case thickness, dial texture, and the beat rate of the movement. Those three tell you most of what the photos did not.