Quick answer
The Royal Oak 67651 is Audemars Piguet's 33mm quartz Royal Oak, best known in steel with a diamond-set bezel. On a replica, four things decide whether it looks right on the wrist: the case diameter and thickness, how the diamonds sit in the bezel, the dial finish and printing, and the bracelet taper into the clasp. Get those four right and the watch reads correctly from arm's length. Miss any one of them and the eye catches it fast.
What the 67651 actually is
This is a small Royal Oak. The case measures 33mm across and sits thin, roughly 7mm, because there is no rotor inside. It runs a quartz movement, and AP's own reference for this line is the calibre 2713. Water resistance on the factory piece sits around 50m. The octagonal bezel carries eight visible screws, a date window shows at 3 o'clock, and the bracelet is integrated with the case, tapering down to a folding clasp.
Finishes vary. Steel with a diamond bezel is the common version, but the reference also exists in yellow gold and pink gold, and some variants add diamonds to the case or the bracelet as well. Diamond count and total carat weight shift with the version, landing in the 0.6-carat range for the standard bezel treatment.
Size and who it fits
33mm is not a unisex compromise. It wears like a small watch. On a 6 to 6.5 inch wrist it sits close to the bone, and on anything above 7 inches it looks deliberate and slight. That matters for a replica, because a dealer who ships a 37mm case and calls it a 67651 is selling you the wrong watch. Measure first, then compare against the case number.
The quartz question
Many buyers assume quartz means cheap. Here it does not, because the original is quartz too. A replica with a decent Swiss or Japanese quartz module will tick once per second like the real thing. If someone offers you an "automatic 67651," that is not a 67651. It might be a fine watch, but it is a different reference.
Where replicas fall apart
- Bezel setting. Factory diamonds sit flush, evenly spaced, with the metal polished between them. Cheap replicas show gaps, uneven heights, or stones that catch light at odd angles.
- Dial. Versions differ, so match your reference. Some carry a textured tapisserie surface, others a smooth sunburst finish with diamond hour markers. Look at the AP logo placement, the date font, and whether the printing sits crisp under a loupe.
- Bracelet. The links should taper in a smooth line and the clasp should close with a firm, quiet click. Loose end links and a rattling clasp are the fastest giveaway.
- Case finishing. Brushed top surfaces, polished bevels, and sharp edges where they meet. Soft, rounded bevels read as cast, not machined.
Before you commit
Ask for a straight-on photo of the dial, a macro of the bezel, and a shot of the caseback with the reference engraving. Ask the seller to confirm case diameter in millimeters rather than calling it "small" or "ladies." Confirm the movement type in writing. If a listing is vague on any of those points, that is the answer you need.
Living with it
Quartz means little maintenance. A battery swap every couple of years, a wipe with a soft cloth, and keeping it away from hot water and steam will cover most of it. The diamond bezel is the fragile part. It will not survive a knock against a doorframe the way a plain steel bezel will, so treat that edge with care.