Short answer
The reference 6002A does not exist. Patek Philippe lists the Sky Moon Tourbillon as the 6002G, a white gold watch. The letter A signals stainless steel elsewhere in Patek's numbering system, so any listing that calls the watch a 6002A is either mislabelled or describing a copy built to imitate the 6002G. A genuine 6002G leaves the workshop in a very small number of pieces each year and combines a hand-engraved case, a grand feu enamel dial, a minute repeater, a tourbillon and a perpetual calendar. It trades in seven figures. Every one of those facts gives you a test to run before money changes hands.
What you need before you start
- A 10x jeweller's loupe
- Digital calipers and a jeweller's scale
- A small magnet
- The reference photographs published by Patek Philippe for the 6002G
- Any service paperwork, box and certificate offered with the watch
- Bright, angled daylight for dial inspection
Step-by-step authentication
- Read the reference number engraved on the caseback and compare it with the number printed on the certificate. It should read 6002G or a 6002G dash variant, never 6002A.
- Measure the case with calipers and weigh it. The genuine watch is about 42.8 mm across in white gold, so a case that measures close to 40 mm or feels light in the hand points to a steel copy.
- Hold the magnet near the case and bracelet. It should not stick. White gold is not ferromagnetic, while many budget copies use plated steel that a magnet will pull.
- Study the case engraving with the loupe. Patek's engravers cut the scrolling pattern by hand, so the lines vary in depth and leave tiny tool marks that change direction. Machine-stamped or laser-etched patterns repeat identically across the case.
- Examine the dial surface at an angle. Grand feu enamel has a deep, glassy pool and shows small surface irregularities under a loupe. Painted or printed imitations look flat, with visible dot patterns at the star markers.
- Compare the dial layout with the official photographs, checking the position of the calendar indications, the sky chart, the moon phase and the printed text. Copies almost always shift a subdial or use a heavier font.
- Check the hands with the loupe. The genuine hands are polished on every surface, with no burrs at the tips and no ridges along the edges.
- Activate the minute repeater away from background noise. A genuine 6002G strikes on the hour, quarter and minute with a clear, sustained chime on cathedral gongs. A thin, rattling or weak sound is the strongest single warning sign.
- Look through the caseback with the loupe. Patek internally angles the bridges by hand, adds crisp bevels and engraves the movement plate. Copies show rounded, dull bevels, uneven perlage and stamped text.
- Match the serial number on the movement with the serial number on the caseback and on the certificate. All three should agree and the engraving should look cut, not printed.
- Ask for the original invoice or a Patek Philippe service record and call the authorised service centre to confirm the serial number.
- Arrange independent authentication with a watchmaker who holds Patek Philippe parts access before you finalise the purchase.
Red flags that end the inspection
- A price far below the auction range for a 6002G
- Any use of the term 6002A, stainless steel or "steel 6002"
- A seller who refuses an in-person inspection or a deposit-backed authentication
- Photographs that blur the dial text, the case engraving or the movement
- Certificates printed on paper that does not match genuine Patek stock, with mismatched fonts or a shifted seal
Why the paper trail matters as much as the watch
The 6002G changes hands through a small circle of collectors, dealers and auction houses, and most of those transactions come with documented ownership. Ask for the chain of ownership, the original presentation box, the certificate and any service history. A seller who owns a seven-figure watch can produce those items without hesitation. When the watch arrives without them, treat the offer as a copy until a qualified watchmaker opens the case and confirms the movement internally.