ISO 3160-1:1998

Overview

ISO 3160-1:1998 - Watch-cases and accessories - Gold alloy coverings - Part 1: General requirements defines general requirements for gold-alloy coverings applied to watch cases and their accessories, including bracelets. It sets definitions, minimum gold content, nominal coating thicknesses, marking rules and references to test and measurement methods. This standard is essential for consistent quality, consumer information and regulatory compliance in horology and metal finishing.

Key topics and requirements

• Scope: Applies to watch-cases, bracelets and related accessories receiving gold-alloy coverings.
• Definitions: Distinguishes plaqué or (gold plated), plaqué or laminé (gold-clad/rolled gold) and coiffe or (gold cap). Also defines surface significative (surface essential to appearance/function) and titre (gold fineness in millièmes).
• Minimum gold content: The alloy fineness (titre) for all covering types must be at least 585 millièmes (commonly referred to as 14 carat).
• Nominal coating thicknesses (with ±20% tolerance):
  • Plated gold (GP) and rolled gold (GR): 5, 10, 20, 40, 80 µm
  • Gold cap (GC / coiffe or): 200, 250, 300 µm
• Measurement and testing:
  • Thickness measurement and fineness determination are to follow methods given in ISO 3160-2.
  • Abrasion and wear tests are specified in ISO 3160-3.
• Marking rules:
  • Marks must include type letters (GP, GR, GC), nominal thickness in µm and a maker’s or responsibility punch.
  • Example marks: GP 10, GR 20, GC 250.
  • Marking is mandatory for coverings ≥ 5 µm, forbidden for coatings < 5 µm; maker’s punch is always required.
  • When parts of a case have different thicknesses, the smallest applicable value must be indicated; composition of each part must be described truthfully.

Applications and users

• Manufacturers of watch cases, bracelets and accessories for product specification and quality control.
• Metal finishers and platers implementing gold plating/laminating/capping processes.
• Quality assurance and testing laboratories using ISO 3160-2/3 for measurement and abrasion testing.
• Buyers, importers and regulatory bodies verifying marking, composition and minimum performance.
• Designers and procurement teams requiring standardized coating specifications for durability and appearance.

Related standards

• ISO 3160-2 - Determination of fineness, thickness, corrosion resistance and adhesion (measurement methods).
• ISO 3160-3 - Abrasion resistance tests for coating types on standardized specimens.

Keywords: ISO 3160-1:1998, watch cases, gold alloy coverings, gold plating thickness, GP GR GC marking, gold cap, watch bracelets, metal finishing standards.