Short answer
A fake yellow gold Audemars Piguet Royal Oak fails three checks in the first minute: weight, hallmark, and movement. A genuine 18k yellow gold Royal Oak on a full bracelet weighs about 150 g. Gold-plated copies weigh less, often 90 g to 130 g. Genuine casebacks carry a 750 stamp and a Swiss precious-metal hallmark. Copies carry a laser-etched 750 or no stamp. Genuine watches run in-house calibres. Copies run quartz or a decorated third-party movement.
Weight and metal content
18k gold is 75 percent gold. It has a density near 15.5 g/cm3. Brass sits near 8.5 g/cm3 and steel near 7.8 g/cm3. A gold Royal Oak bracelet holds about 100 g of gold alloy, worth several thousand dollars at current metal prices. No copy sells near that metal value. A $300 to $1,500 copy uses brass, steel, or a plated case. A jeweller with an XRF scanner reads the surface in seconds and reports the gold percentage. Plated cases show a thin layer over base metal. Scratches on the clasp and lugs expose the color underneath. Swiss law requires the 750 fineness mark and the Swiss official precious-metal hallmark on gold cases made or sold there.
Caseback, reference, and records
AP engraves the full reference on the caseback, such as 16202BA.OO.1240BA.02 for the yellow gold Jumbo. A serial number sits on the caseback edge. AP keeps manufacturing records and can confirm a serial through its service department. The Extract from the Archives letter states the date of manufacture, the original model, and the delivery country. Most copies cannot survive that check. Engraving depth matters too. Genuine AP text is cut clean and sits below the surface. Copies use shallow laser etching or acid marks with rough edges.
Movement
The Royal Oak Jumbo 16202 uses calibre 7121. The movement measures 4.05 mm thick and runs 55 hours on a full wind. The 26240 chronograph uses calibre 4401 with a 70-hour reserve. Both are in-house. Copies use quartz, or a Miyota or Seiko base with a printed rotor and a fake bridge plate. The 7121 beats at 4 Hz, which gives eight ticks per second. A smooth, gliding seconds hand on a Jumbo points to quartz.
Case, bezel, and bracelet details
The 16202 case measures 8.1 mm thick and 39 mm across. Copies often run 9 mm to 11 mm thick. Eight hex screws hold the bezel. On genuine watches the screws thread into the case. Cheap copies glue the screw heads onto the bezel or mold them into the metal. The Petite Tapisserie dial grid is cut into the dial blank. Copies print the grid, which gives less depth and softer lines. Date wheel fonts differ as well. Genuine windows sit tight to the numeral. Copies show wide gaps and a flat font. The Royal Oak bracelet narrows toward the clasp. Copies keep thick links near the clasp.
Price signals
A new yellow gold Royal Oak Jumbo lists above $60,000. Used examples trade near or above list. A yellow gold chronograph lists higher. Any offer far below market for a solid gold watch points to a copy, a swap, or a stolen watch. Counterfeit sales are illegal in the US under 18 U.S.C. 2320.
What a replica listing discloses
Replica listings name the plating and the movement. Common claims include "18k gold plating, 5 microns" and "clone 7121 movement." Five microns equals 0.005 mm. That layer wears off at the clasp, the crown, and the link edges within months of daily wear. A listing may also claim 904L steel. That states the base metal, not the gold content. A plated copy is not solid gold and will not read as 750 on an XRF scan.
Checks to run before you buy
- Weigh the watch on a jeweller's scale.
- Ask for an XRF reading on the case and bracelet.
- Read the caseback engraving with a loupe.
- Match the reference number to the dial color and case metal.
- Confirm the serial with AP service.
- Have a watchmaker open the caseback and name the calibre.