The short answer
A replica Rolex Day-Date 128347 copies the outside of a gem-set Day-Date 36. It cannot copy the solid precious-metal case, the diamond grading, or the calibre 3255 inside. When you inspect one, judge it on three things: dimensions, dial furniture, and the movement. A first copy that measures 36 mm at the case, prints the day and date in the correct fonts, and runs a 28,800 vph automatic will read close on the wrist. A copy with an oversized case, painted indices, or a 21,600 vph movement will not.
Genuine specs to compare against
- Case: 36 mm diameter in precious metal, diamond-set bezel on this reference
- Movement: calibre 3255, automatic, 28,800 vph, about 70 hours of power reserve
- Bracelet: President, three-piece semi-circular links, hidden Crownclasp
- Water resistance: 100 m
- Display: day window at 12 o'clock, date window at 3 o'clock
Prerequisites
- A digital caliper
- A 10x loupe
- A gram scale
- A soft cloth and a bracelet sizing tool
Inspection steps
- Measure the case with calipers at the 3 and 9 o'clock flanks, crown excluded. A 128347 copy should read 36.0 mm to 36.3 mm. Anything over 37 mm is a different case.
- Check thickness from the caseback to the top of the crystal. The genuine watch sits near 12 mm. A copy that reads 14 mm will ride high on the wrist.
- Set the day first, then the date, using the crown in position 2. The day disc should snap through the window without dragging. A slow or half-locked change points to a cheap date module.
- Study the day and date fonts through the loupe. Genuine printing is crisp with even strokes. Blurry edges, thick serifs, or a date disc that sits low in the window are common tells.
- Inspect the diamond bezel under magnification. Count the prongs on one stone and compare with its neighbors. Stones should sit level, in one row, with no gaps and no cloudy examples.
- Turn the watch over and check the bracelet. Each President link has three parts. Run a finger along the center link for sharp edges, then check the clasp for the hidden Crownclasp design.
- Weigh the watch on the scale. Solid gold Day-Date 36 models run well past 150 grams with a full bracelet. A steel or plated copy usually lands between 100 and 130 grams.
- Wind the crown 20 turns and set the watch down. Tilt it and listen to the rotor. A grinding sound or a rotor wobble means the movement needs service.
- Read the engraving between the lugs at 12 and 6 o'clock. Reference numbers, serial, and hallmarks are laser-cut on the genuine piece. Stamped or shallow engraving is a copy.
- Check the crystal and the cyclops. The date should magnify about 2.5 times with no blue tint and no edge distortion.
- Request a pressure test before wearing the watch near water. Case gaskets are the first part to fail on replica cases.
- Confirm which movement sits inside and whether parts are available. Common choices are an ETA clone, a Miyota, or a decorated Chinese automatic.
Red flags
- Case diameter off by more than one millimeter
- Day window that sits off-center under 12 o'clock
- Diamonds glued in place with no visible prongs
- Plating worn through to steel on the caseback edges
- No movement name given when you ask
Legal and practical note
Counterfeit watches that carry the Rolex name and coronet are illegal to import into the United States and illegal to sell. Keep that in mind when you buy, and never pass a copy off as a genuine watch in a sale or a trade.