Short answer
The Audemars Piguet reference 26574 is a 41 mm Royal Oak Perpetual Calendar. The genuine watch runs caliber 5134. Replicas sold under this reference number do not run a true perpetual calendar. Most use a Miyota 9015 or a Chinese copy of it, with a calendar module stacked on top. The day, date, month and moon phase subdials move, but the movement counts 31-day months. After February the date reads 31 until someone resets it. That fault is mechanical, not cosmetic, and no photo fixes it.
Genuine reference facts
- Case: 41 mm, steel on the 26574ST, 9.5 mm thick.
- Caliber 5134, automatic, about 40 hours of power reserve.
- Indications: day, date, month, leap year, moon phase and week of the year.
- Bracelet: integrated Royal Oak links, folding clasp.
Replica builds on the market
Three builds appear in listings. The first is a 9015 with a decorative plate and printed subdials that do not move. The second is a 9015 with a working day and date, no month and no leap year. The third, sold as "A5134," adds a module that drives all four subdials and costs more. Case diameter on all three sits near 41 mm. Case thickness is the common failure: 11 mm to 12.5 mm against 9.5 mm on the original.
Checks before payment
- Ask for a caliper photo of the case back, not a tape measure.
- Confirm the hand stack. Hour, minute and subdial hands must sit at one level.
- Inspect the moon phase disc. Stamped metal on the real watch, printed photo on most copies.
- Count bracelet links and compare the taper toward the clasp.
- Request video of the midnight date change. A perpetual calendar jumps once.
What no copy matches
The 5134 module is thin, and the case is 9.5 mm tall. A stacked module under a 9.5 mm case demands plates that few replica factories cut. Finishing on the lever surfaces under the caseback is another gap. Sellers who quote 9.5 mm at a low price are quoting the original spec, not the watch they ship.
Legal position in the US
18 U.S.C. § 2320 makes trafficking in counterfeit goods a federal offense. A first conviction carries up to 10 years in prison. US Customs can seize a shipment at the border, and the buyer's name stays on the record.