Short answer

Fake Patek Philippe 3970 watches are copies of a real Patek Philippe perpetual calendar chronograph. Patek Philippe made the Reference 3970 from 1986 to 2004. Genuine examples sell at auction for six figures. Copies sell for a few hundred dollars. The dial layout is easy to copy. The movement, the case, and the caseback are not.

What the Reference 3970 is

  • Reference 3970 entered the catalog in 1986 and replaced the Reference 2499.
  • Movement: caliber CH 27-70 Q. Manual wind. Base is the Lemania 2310. Column wheel chronograph with a horizontal clutch. Perpetual calendar with moon phase and leap year.
  • Beat rate: 18,000 vibrations per hour, or 2.5 Hz.
  • Case: 36 mm diameter, about 13 mm thick. Yellow gold, rose gold, white gold, and platinum. The reference code carries the metal letter, so a watch reads 3970J, 3970R, 3970G, or 3970P.
  • Dial: two calendar apertures at 12 o'clock and three subdials.
  • Production ran to 2004. Published estimates of total output vary by source.

Points where copies fail

  • Subdial position. A Valjoux 7750 has subdials at 12, 9, and 6. A 3970 has subdials at 3, 9, and 6. The mismatch shows at a glance.
  • Movement. A real 3970 shows a column wheel and a slow beat. Copies use a 7750 at 28,800 vph, a Seagull ST19, or quartz. A quartz copy has a small seconds hand that ticks once per second.
  • Case size. Copy cases measure 38 mm to 42 mm wide and 14 mm to 16 mm thick. The real case is 36 mm wide.
  • Caseback. The 3970 has a solid snap caseback with the Calatrava cross and gold hallmarks. Many copies use a screw back or a sapphire display back.
  • Calendar apertures. Real apertures are cut to match the printing. Copy apertures show white edges and the discs sit too deep.
  • Moon phase disc. The real disc has a set star field and a specific moon profile. Copy discs are flat with wrong printing.
  • Pusher feel. The start pusher on a 7750 copy feels stiff and the chronograph hand jumps on start.

Price and market

Real 3970 results at Phillips and Christie's land between about $100,000 and $400,000. Metal, series, and condition move the number. Platinum and rose gold examples bring more than yellow gold. Copies sit between $300 and $1,500. A 3970 with box, papers, and a service record sells in a different band than a loose watch.

Legal position in the US

18 U.S.C. § 2320 covers trafficking in counterfeit goods. A first offense carries up to 10 years in prison and a $2 million fine for an individual. U.S. Customs and Border Protection seizes counterfeit watch shipments at ports of entry and destroys them. Trademark holders can file civil suits for damages and legal fees. Import rules differ from resale rules, and a shipment can be seized either way.

Checks before you buy

  1. Weigh the case. Solid gold weighs more than a plated copy.
  2. Time the watch on a timegrapher. Look for 18,000 vph, not 28,800.
  3. Ask for the reference code and the serial number.
  4. Order an Extract from the Archives from Patek Philippe. The maker issues this document for a fee and it lists the original case metal, dial, and sale date.
  5. Compare dial printing and hand shape to known auction photos.

No single check proves a watch is genuine. A 3970 with matching papers, a matching serial, and an Extract from the Archives is the safest case. Anything else is a guess.