First, we always recommend purchasing a pre-owned Audemars Piguet Royal Oak through a verified seller, such as WatchBox. To avoid purchasing a fake Royal Oak, here are a few things to look out for: Thickness - Authentic Royal Oaks are 9.8mm thick, fake models tend to be thicker than 9.8mm. Tapisserie on watch dial - Authentic Royal Oak dials are embossed smoothly, and aren’t overly thick. Screw sizes on bezel - Real Royal Oak models feature symmetrical and consistent screw sizes on the bezel. Engraved details on back - Fake models are known to have “AUDEMARS” in thick text, and “PIGUET” in thin and too tall text. This is found on the back of the watch. Fit and finishing - Authentic Royal Oak models don’t rust and the materials have a high-quality feeling. “Swiss Made” on the dial of the watch - Look for the “Swiss Made” text at the 6 o’clock area of the dial in real models. AP logo on crown and clasp - Check for proper font weight.