The short answer
Buy the automatic. The quartz replica costs less and sits thinner on the wrist. It also drops the two details buyers inspect first: the sweep of the second hand and the movement under a sapphire caseback.
Quartz makes sense in one case. You want a slim yellow gold dress watch at the lowest price and you never plan to open the caseback or time the sweep.
Second hand and beat rate
A quartz movement runs on a 32,768 Hz crystal. The circuit divides that signal down to one pulse per second, so the second hand jumps 60 times a minute. An automatic at 28,800 vibrations per hour moves the hand 8 times a second. At 21,600 vph it moves 6 times a second. Put the two side by side on a table and the ticking hand shows inside a minute.
Case metal and weight
Yellow gold replicas come in three builds: gold plated steel, gold plated brass, and solid 18k gold. Plating runs about 3 to 10 microns. Density tells the rest. 18k yellow gold sits near 15.5 g/cm3. 316L steel sits near 8.0 g/cm3. A solid gold case weighs about twice what the same case weighs in steel, and the hand feels it.
Quartz builds save thickness. A battery cell and a thin movement let the case sit 1 mm to 2 mm lower than an automatic of the same diameter. On a 38 mm dress watch that reads as a flatter case on the wrist.
Dial and hands
Breguet hands carry a hollow circle near the tip. Stamped replica hands show a flat edge under a loupe. Guilloche dials on the original are cut on a rose engine. Most replicas print the pattern. Tilt the dial toward a light: a printed pattern shows no depth change across the rings. Ask the seller for a macro photo of the dial center and the hand tip before you pay.
What Breguet builds
Breguet puts mechanical calibres in most of its catalog. The Classique 5177 uses self-winding calibre 777Q in an 18k yellow gold case of 38 mm. Breguet lists quartz in some ladies references, with Reine de Naples as the main line. I could not confirm a yellow gold Breguet reference built on a quartz calibre. Treat any replica sold as a Breguet yellow gold quartz watch as a copy you should match to a reference number first. If the seller cannot give the number, the watch copies no real model.
Four checks before you pay
- Sweep test. Film the second hand for 10 seconds. 8 steps per second points to 28,800 vph. 6 steps points to 21,600. One step per second is quartz.
- Caseback. Look at engraving depth and font weight. Solid gold cases carry hallmarks. Plated cases skip them or stamp them shallow.
- Weight in grams. Ask for a photo of the watch on a scale. A 38 mm solid gold case lands well above a plated steel case of the same size.
- Crown and stem. A quartz build uses a short stem. Pull the crown and count the positions: time setting, date if fitted, and no other function.
Options
- Automatic Classique style, yellow gold, 38 mm. First pick. Sweeping hand, open caseback, and closer case weight when the build is solid gold.
- Quartz yellow gold, slim case. Second pick. Lower cost, thinner profile, ticking hand. Accept the caseback as decoration.
- Automatic with a closed caseback. Third pick. Costs less than the open caseback build and keeps the movement out of view, which removes one point of comparison.
Ask for the price gap between options one and two in writing. The difference varies by seller, and I have no verified figure to quote.