Short answer
A genuine Audemars Piguet Royal Oak in rose gold has a case, bezel, bracelet and clasp made of solid 18k gold. A counterfeit version uses a steel or brass core under a thin gold layer, or a gold-filled shell. The two look alike in a photo. They differ in weight, hallmarks, engraving depth, movement and price.
What the gold claim means
Rose gold is a gold and copper alloy. At 18k the mix is 750 parts gold per 1,000 parts metal, with copper and a small share of silver. Audemars Piguet stamps gold cases with the fineness. In the Swiss precious metal control system the official mark for 18k gold is the head of a St. Bernard dog. A plated case has no such mark struck into the metal.
The U.S. Federal Trade Commission sets the rules for gold descriptions in its Jewelry Guides. An item with a gold coating is described as gold plated or gold filled, not as gold. A case marked as gold that is a plating does not meet that standard.
Weight and feel
Solid 18k gold runs about 15.2 to 15.6 grams per cubic centimeter. Stainless steel runs about 7.9. A gold Royal Oak on a full bracelet sits well above the weight of the same size watch in steel. A plated copy on a steel case adds a few grams of gold at most. Audemars Piguet does not publish a weight for every reference, so compare against a known watch of the same reference, not against a figure from a listing.
Points to check
- Marks. Look for the fineness stamp and the Swiss hallmark on the caseback and clasp. Check that they are struck into the metal, not printed on the surface.
- Caseback engraving. Reference and case numbers sit in a straight line with even depth. On copies the font is wide and the cut is shallow.
- Movement. The 39 mm Jumbo runs calibre 2121 in ref 15202 and calibre 7121 in ref 16202. The 41 mm ref 15500 runs calibre 4302. Replica movements often start as a Miyota or Seiko unit with a decorated rotor plate. The date font and the date window position show the difference.
- Bracelet. Solid gold links have no hollow rattle. Plated links wear through at the clasp and on the link edges, and the base metal shows as another color.
- Records. Audemars Piguet holds a file for each case number and offers an Extract from the Archives. A seller who will not submit the number has no answer.
Reference points
- The Royal Oak launched in 1972, designed by Gerald Genta.
- Gold references carry an OR suffix in the code, as in 15500OR. Steel uses ST.
- Rose gold Royal Oak retail prices sit in the tens of thousands of dollars and move with each collection update.
Price gap
A counterfeit rose gold Royal Oak sells for a few hundred dollars. A genuine one in the same metal sells for tens of thousands. Gold plating over base metal costs little, so the two prices describe two different objects.
What photos cannot settle
A photo shows no weight, no hallmark depth and no movement. A video shows the same. Any check that ends with a look at the pictures has not tested the gold.