Short answer
Reference 210.30.42.20.01.001 is the Omega Seamaster Diver 300M in 42 mm steel with a black ceramic dial and a steel bracelet. Hippocampus is the seahorse emblem on the Seamaster line, so sellers use the word for Seamaster copies. A replica of this reference is a watch built to look like that model. It holds no Omega parts, no METAS certificate and no factory support.
What the reference number covers
Omega builds the Seamaster Diver 300M family on one case platform. The code lists case size, dial, bezel and bracelet choices. The 42 in the string marks the 42 mm case. Omega does not publish a full key for every digit.
Genuine specs
- Case: 42 mm steel, 300 m water resistance
- Bezel: black ceramic with white enamel dive scale
- Dial: black ceramic, laser-engraved waves
- Movement: Omega caliber 8800, Master Chronometer
- Power reserve: 55 hours
- Magnetic resistance: 15,000 gauss
- Crystal: domed sapphire, anti-reflective on both faces
- Helium escape valve at 10 o'clock
- US list price: above $6,000. Confirm the current number with Omega.
What first copy replicas of this reference hold
Sellers state these parts. Independent pressure and timing tests are rare.
- Case: 316L or 904L steel, 42 mm, 13 mm to 14 mm thick
- Dial: printed waves on ceramic or on painted metal
- Movement: Chinese automatic, Miyota 9015 or Seiko NH35; some sellers name a clone of the 8800
- Crystal: mineral on low grades, sapphire on high grades
- Water resistance: stated at 30 m to 50 m, with no test report
- Bracelet: steel with a push-button clasp or a copy of the Omega clasp
Gaps between the two
METAS tests each Master Chronometer across eight protocols, including exposure to 15,000 gauss and a 300 m pressure test. Copies skip the lab. A replica has no serial record, no Omega service and no parts network. Resale value drops to near zero. The genuine reference keeps a used market.
Legal status in the US
18 U.S.C. § 2320 makes trafficking in counterfeit goods a federal crime. A first offense carries up to 10 years in prison; a repeat offense up to 20 years. Trademark owners can sue under the Lanham Act, 15 U.S.C. § 1114. CBP inspects and seizes counterfeit shipments at ports. The personal-use exemption does not cover counterfeit goods.
Checks before you buy
- Ask for the caliber name and a photo of the movement.
- Ask for the steel grade: 316L or 904L.
- Ask for the crystal type: sapphire or mineral.
- Ask for a pressure test result. Assume none exists.
- Read the return terms and the payment method.