Answer first

Forged carbon is chopped carbon strand set in resin and pressed in a mold. Each case shows a random swirl. Audemars Piguet put the material on the Royal Oak Offshore in 2007. Replica versions copy the pattern. Most use a steel core with a carbon skin, an Asian 7750 movement, or quartz. Genuine forged carbon Offshores trade near $25,000 to $45,000. First copy replicas list from $150 to $400.

What forged carbon is

Carbon strands are mixed with epoxy resin and loaded into a steel mold. Heat and pressure cure the part. Strands sit at random angles, so no two cases match. The surface shows a marbled black and gray swirl with no weave. Density lands near 1.5 g/cm3. Steel 316L sits near 8.0 g/cm3. Resin ratios and mold pressure at Audemars Piguet are not public.

References that used the material

The Royal Oak Offshore Chronograph ref. 26176FO arrived in 2007 in a 42 mm case. The Royal Oak Offshore Grand Prix followed in 2010 and used forged carbon in the case. Later 44 mm chronographs used it in limited runs. Audemars Piguet does not publish production totals for these references.

Weight and size

A 42 mm forged carbon Offshore on a rubber strap weighs about 90 g. A steel case of the same size weighs about 160 g. Most replicas do not match those figures. A plated steel case adds 40 g or more. A plastic case drops under 70 g. Case width runs 42.0 mm. Case thickness runs about 15 mm at the crystal.

Movement inside

The genuine 42 mm chronograph used AP caliber 3126/3840, built on caliber 3120 with a chronograph module. Asian clones use the 7750 layout and beat at 28,800 vph. Check the balance wheel through the caseback. Check rotor engraving and font depth. A quartz movement ticks one step per second and rules out any mechanical caliber. I cannot confirm subdial layouts for every reference from published data, so compare hands against reference photos.

Caseback and hardware

Royal Oak Offshore casebacks carry eight hexagonal screws. Replicas may ship with the wrong screw count, shallow engraving, or a sticker. Crown and pusher guards are rubber coated on some references and ceramic on others. Check thread feel on the crown. Cross threading shows up on low grade cases.

Water resistance

Genuine Offshore chronographs rate to 100 m. Most replicas do not get pressure tested. A case that leaks ruins the movement. Treat any replica as not water resistant unless the seller shows a pressure test result.

Legal status in the United States

19 U.S.C. 1526 lets U.S. Customs and Border Protection seize and destroy goods that carry counterfeit marks. Trafficking in counterfeit goods falls under 18 U.S.C. 2320, with a first offense maximum of 10 years in prison. Trademark owners can sue for damages under the Lanham Act. This is not legal advice.

Price bands

Genuine 42 mm forged carbon Offshores trade around $25,000 to $45,000. First copy replicas list from $150 to $400. Higher grades with a decorated 7750 run $500 to $900. Prices above $1,000 are not common for replica Offshores. Audemars Piguet service is not available for a counterfeit, so repairs fall to independent watchmakers.