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GOLD

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2. General description

Gold is a precious metal used in watchmaking for several centuries, mainly for its aesthetic qualities, its corrosion resistance and its symbolic value. It is used to make cases, bracelets, External parts (case, dial, hands) components (dials, hands, etc.) and, more rarely, certain technical parts, particularly wheel plates, or even bridges and mainplates.

In its pure form, Gold is very ductile, but has low mechanical strength, which limits its use. Its Alloys not only improve its mechanical properties but also allow its shade to be adjusted, giving rise to a wide variety of standardized colors.

3. Gold Alloys in watchmaking

Yellow gold and Rose gold (pink gold): standardized shades (2N to 5N)

In watchmaking and jewelry, Gold shades are codified according to a standardized European scale, generally ranging from 1N to 5N, based on the proportion of Copper and Silver in the Alloy.

👉 The higher the Copper content → the redder the shade
👉 The higher the Silver content → the paler yellow the shade

The main shades:

• 2N (light yellow Gold)
  Pale yellow shade, rich in Silver
  Discreet appearance, slightly greenish
• 3N (standard yellow Gold)
  Balanced hue, the most classic in watchmaking
  Good aesthetic compromise
• 4N (Rose gold (pink gold))
  Pinkish hue, enriched with Copper
  Widely used in contemporary watchmaking
• 5N (red Gold)
  Pronounced red hue
  High proportion of Copper

This standardization ensures color consistency between components and between manufacturers.

White Gold

Obtained by adding white Metals:

• Palladium (high-end Alloy)
• Nickel (less commonly used today)

Characteristics:

• Grey-white hue
• Often coated with rhodium
• Good mechanical resistance

Depending on the nature and content of the alloyed metal, white Gold (especially nickel alloys) sometimes needs to be rhodium-plated to achieve a perfectly white shine.

Other variants

• White gold (grey gold) → palladium-based alloys
• Green gold → gold and Silver
• Black gold → surface treatments or specific alloys

Modern technical alloys

Some manufactures develop proprietary alloys for various purposes:

• Increased scratch resistance
• Color stability over time
• Better mechanical strength
• Marketing argument

4. Concept of fineness and hallmarks

The fineness of Gold

Fineness refers to the proportion of pure Gold in the Alloy.

• 24K (999‰) → pure Gold
• 18K (750‰) → 75% Gold
• 14K (585‰) → 58.5% Gold

👉 In watchmaking, the standard is 18 carats, offering an optimal balance between purity and strength. A 22K Alloy is often used for making the oscillating weights of automatic Movements.

The hallmark

The hallmark is an official mark guaranteeing:

• The title of the alloy
• Its legal compliance
• Sometimes its origin

There are:

• Title hallmark → purity of the metal
• Maker’s hallmark → manufacturer

5. Treatments and finishes

Gold can be:

• Polished
• Satin-finished or brushed
• Guilloché or engraved
• Rhodium-plated (white gold)
• Treated (vapor deposition coatings, etc.)

6. Watchmaking applications

Gold is used for:

• Cases
• Bracelets
• Dials
• Hands and Index (hour marker)
• Oscillating weights
• Wheel boards (rarely)
• Bridges and main plates of exclusive watches

7. Advantages and limitations

Advantages

• Unalterable
• Prestigious aesthetics
• Wide variety of shades
• Excellent finish
• Non-magnetic
• Mass significant

Limitations

• High cost
• Mass significant
• Sensitivity to scratches
• Need for Alloy