Identify Your Mark

Serial Number Engraving

A unique alphanumeric code engraved on the case back that identifies your individual watch. This number is typically used for warranty registration, service history, and authentication.

Model Number Stamp

An alphanumeric code stamped on the case back that identifies the specific watch model or product line. This number is essential for ordering replacement parts and identifying your watch's specifications.

Water Resistance Rating (Case Back)

A marking indicating the watch's tested water resistance depth, typically shown in meters, feet, bar, or ATM. This rating describes laboratory test conditions, not actual diving depth recommendations.

Case Material Marking

An engraving or stamp indicating the material the watch case is made from, such as stainless steel, titanium, or gold. This marking helps verify authenticity and informs care and maintenance decisions.

Crystal Press Back Symbol

A small symbol on the case back indicating it should be opened with a crystal press tool rather than unscrewed. This marking guides watchmakers on the correct method for case back removal.

Japan Movement Stamp

A case back marking indicating the watch uses a movement manufactured in Japan. This is commonly seen as "JAPAN MOVT" or "JAPAN MOVEMENT" and denotes the origin of the caliber inside.

EXPLORE JEWELRY HALLMARKS

925 Sterling Silver

The 925 stamp indicates sterling silver, meaning the piece is composed of 92.5% pure silver and 7.5% other metals, typically copper. This is the international standard for sterling silver jewelry.

999 Fine Silver

The 999 stamp indicates fine silver, meaning the piece contains 99.9% pure silver. This is the highest standard of silver purity used in jewelry and bullion.

750 / 18K Gold

The 750 stamp indicates 18-karat gold, meaning the piece contains 75% pure gold. This is one of the most popular and highly regarded gold purities for fine jewelry worldwide.

585 / 14K Gold

The 585 stamp indicates 14-karat gold, meaning the piece contains 58.5% pure gold. This is the most popular gold purity for jewelry in the United States due to its excellent balance of beauty and durability.

375 / 9K Gold

The 375 stamp indicates 9-karat gold, meaning the piece contains 37.5% pure gold. This is the minimum gold purity legally recognized as gold in the UK, Ireland, and several other countries.

916 / 22K Gold

The 916 stamp indicates 22-karat gold, meaning the piece contains 91.6% pure gold. This high-purity gold is especially popular in South Asian, Middle Eastern, and Southeast Asian jewelry traditions.

EXPLORE OUR BRANDS

Rolex

If there is one watch brand whose markings are studied more than any other, it is Rolex. Founded in 1905 by Hans Wilsdorf, the company pioneered the waterproof Oyster case, the Perpetual self-winding rotor, and the Datejust date display. Rolex's prominence in the pre-owned market — and the prevalence of counterfeits — makes familiarity with its case back codes, serial number formats, and clasp markings especially valuable for anyone buying or inheriting one of these watches.

Omega

Omega's case backs are among the most distinctive in watchmaking — the hippocampus seahorse medallion, the Speedmaster's moonwatch heritage engravings, and the PIC number system all make Omega watches particularly identifiable. Founded in 1848 and now part of the Swatch Group, Omega has a rich catalog spanning dive watches, chronographs, and dress pieces. Their 14-digit PIC number, introduced in the 2000s, is one of the most detailed product identification systems in the industry, encoding everything from collection and case material to dial color and movement type.

Seiko

Seiko's case back markings follow a distinctive caliber-case format (like '7S26-0010') that tells you both the movement and the case design at a glance — once you know how to read it. Founded in 1881, Seiko manufactures everything from sub-$100 automatics to Grand Seiko pieces that compete with Swiss luxury brands. The challenge for collectors is that Seiko has long used single-digit year codes in serial numbers, so a '7' could mean 1967, 1977, 1987, or 1997. Cross-referencing with caliber production dates, dial styles, and factory logos is usually necessary to pin down the decade.

TOPIC GUIDES

Water Resistance Markings on Watches — What Do They Really Mean?

Watch Movement Markings — Caliber Numbers, Jewel Counts & Origin Stamps

Watch Case Material Stamps — Stainless Steel, Gold, Titanium & More

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