The Overseas Perpetual Calendar Ultra-Thin, reference 4300V, is a hard watch to counterfeit. The fastest way to spot a fake is to check three things at the same time: the case size, the dial layout, and the movement behind the sapphire back. A genuine 4300V measures 41.5 mm across and 8.1 mm thick, and its four subdials sit in a fixed arrangement, month and leap year at 12, date at 3, moon phase at 6, day at 9. Most fakes get the thickness wrong, the subdial spacing wrong, or both.
Before you start
- Digital calipers and a gram scale.
- A 10x loupe and a bright, diffused light.
- Reference photos of a known genuine 4300V, front, side, caseback, and movement.
- A watchmaker who can open the case and time the movement.
Step-by-step checks
- Measure the case with calipers. A genuine 4300V is 41.5 mm wide and 8.1 mm thick. Fakes run thick, often past 9 mm, because a stock calendar module sits under the dial.
- Weigh the watch on a gram scale. This reference comes in 18k white gold and 18k pink gold, so the case should feel dense for its size. A light case points to steel with gold plating.
- Check the bezel under a loupe. The Overseas bezel is a notched ring that echoes the Maltese cross, with a crisp line between satin and mirror surfaces. Fakes show rounded notches and blurred finish edges.
- Inspect the calendar correctors on the case flank. Each corrector is a recessed push piece that sits flush with the case band. On a fake they sit proud, sit off center, or carry a rough lip.
- Compare the four subdials. Spacing should be even, with no crowding at 12 where the month and leap year share one dial. Print should be sharp and consistent in weight.
- Look at the moon phase at 6 o'clock. The genuine disc uses a raised gold moon with surface detail against a deep blue sky. Fakes print a flat disc with mismatched stars.
- Study the applied markers and hands. They are gold, faceted, and finished on all sides. Run a fingernail over an edge on a fake and you feel a burr or see paint creep.
- Test the strap release. Press the button at the lug and pull the strap away. The genuine system releases under light pressure, and the same system fits the leather, rubber, and bracelet options.
- Inspect the crown. It is screw down and carries a raised Maltese cross. Threads should catch in a half turn and seat with no wobble.
- Turn the watch over. The sapphire back shows a 22k gold rotor, black polished screws, anglaged bridge edges, and circular graining. Fakes show stamped bridges with no bevel.
- Find the Hallmark of Geneva. The eagle and key are stamped into the movement, and the standard covers the whole watch. A missing or shallow stamp is a red flag.
- Read the caseback engraving with a loupe. Reference and case numbers are cut with sharp walls and even depth. Laser etching on a fake looks shallow and gray.
- Ask a watchmaker to time the movement. Caliber 1120 QP/1 runs at 19,800 vph with a 40 hour power reserve and 276 components. A quartz or a modified stock automatic ends the deal on the spot.
- Verify the serial number and papers. Ask for the original invoice and the Extract from the Archives. Call Vacheron Constantin with the reference and case number before you pay.
- Send the watch for authentication if the seller resists any check. A maker service center is the only final word.
When to walk away
A seller who blocks a movement check, refuses a service center visit, or pushes a cash deal with no papers is telling you what you need to know. Papers and boxes can be copied, so treat them as supporting evidence and not proof. On this reference the movement is the hardest part to fake, and it is also the part most sellers will not let you see.