The single most reliable check on a fake Audemars Piguet ref 26470 is the caseback and the movement behind it. The reference is a 42 mm Royal Oak Offshore chronograph, and the in-house calibre AP fits to it is finished to a level that no mass-produced counterfeit reaches. That is the top pick here because it is the most expensive tell to copy and the one counterfeiters most often get wrong.

Every other check below was judged on three things: how much it costs a counterfeiter to get right, whether you can confirm it without opening the watch, and how often it actually decides a real-versus-fake call on a listing photo or at a table.

1. Caseback and Movement: the Deciding Check

Most steel 26470 examples carry a sapphire display back. Through it you see the base automatic movement AP uses across the Royal Oak line, with Geneva stripes on the bridges, polished bevels along the edges, and a gold oscillating weight engraved with the brand name. Counterfeit display backs usually show a decorated generic automatic or a chronograph module wearing engraved plates. The lettering looks stamped rather than cut, the striping stops short of the bridge edges, and the rotor is plated brass instead of gold.

Pros

  • Hardest element to replicate at counterfeit price points.
  • Visible on any example with a display back, no tools required.

Cons

  • Some references use a solid caseback, which hides the movement.
  • Needs sharp macro photos; dim phone shots hide almost everything.

Use it when: the listing shows a display back and the seller will send close-ups of the rotor and balance area. A refusal to send them ends the conversation.

2. Dial Texture, Printing and Date Wheel

The Offshore dial has a raised waffle pattern that AP calls Mega Tapisserie. Genuine squares are crisp, evenly cut and catch light differently as you tilt the watch. Copies show shallow squares, rounded edges or a flat printed grid. Look at the brand name: genuine printing is razor sharp at magnification, while fakes show bleeding edges, uneven spacing or a font that is slightly too wide. The date wheel on a counterfeit often sits slightly off centre in the window or uses a thinner numeral than AP.

Pros

  • Confirmable from a single straight-on photo.
  • Cheap to check and fast to rule out obvious fakes.

Cons

  • High-end counterfeits have closed much of the gap here.
  • Lighting and camera angle can make a genuine dial look flat.

Use it when: you are filtering many listings quickly and need a first pass before asking for movement photos.

3. Case, Bezel and Crown Guard Geometry

The octagonal bezel sits on eight screws, and the case flanks alternate brushed surfaces with polished chamfers. Counterfeit cases usually look thicker at the lugs, lose the sharp line where brushed meets polished, and use screws with slots that are shallow or unevenly spaced. Check the crown guards and pushers too: they should sit flush with the case band and feel solid when pressed, not loose or gritty.

Pros

  • Visible in any side or three-quarter photo.
  • Proportions are hard to fake without new tooling.

Cons

  • Refinishing by a third party can blur the lines on a genuine watch.
  • Wide-angle photos distort case thickness.

Use it when: you have side-profile shots and want to confirm the case before paying for an inspection.

4. Bracelet, Clasp and Serial Engravings

Genuine bracelets taper smoothly, links flex without rattle, and the deployant clasp carries deep, clean engraving. Counterfeit clasps usually have shallow stamping, misaligned logos and sharp edges on the inside of the folding arms. The serial on the caseback should be cut into the metal, not printed, and it should match the number on the warranty card or archive extract.

Pros

  • Serial matching catches watches built from mixed parts.
  • Clasp quality is easy to feel in person.

Cons

  • Straps and clasps get swapped, so a mismatch is not proof on its own.
  • Older watches may have lost their original paperwork.

Use it when: the seller claims full set. Ask for one photo showing the caseback serial and the card together.

5. If You Are Buying a Replica on Purpose

Buyers who know they want a replica should still apply the same checks, for a different reason: to confirm they are paying replica money and receiving a replica, not a genuine price for a counterfeit. Ask the seller which factory and which movement version, whether the chronograph is a working module or a decorative sub-dial, and whether the watch is sold openly as a replica. An honest seller answers all three. Anyone presenting a counterfeit as genuine stock, or pricing a replica near genuine market value, is the actual risk in this category.

Pros

  • Clear disclosure removes the main source of disputes.
  • Knowing the tells stops you overpaying for a lower tier build.

Cons

  • A replica is never serviceable by the brand and holds no genuine resale value.
  • The tells in sections 1 to 4 do not disappear because the price was low.

Use it when: you are comparing replica listings and want to separate a well-described watch from a vague one.

Quick Pre-Purchase Checklist

  1. Ask for a macro photo of the movement through the display back.
  2. Compare dial printing and date font against a known genuine example.
  3. Check the brushed and polished transitions on the case flanks.
  4. Match the caseback serial against the card or extract.
  5. Meet at a watchmaker for an inspection before money changes hands.

No single tell settles every case. Two or three failing together almost always does.