Base elements → Materials → Mineral materials

DIAMOND

Table of main properties of diamond

 

Property Typical Value Remarks
Density ~3.5 g/cm³ Moderate
Young’s modulus (E) ~1000–1200 GPa Extremely high
Compressive strength ~8000–10000 MPa Extremely high
Hardness (HV) ~8000–10000 HV Extremely high
Hardness (Mohs) 10 Highest known natural hardness
Thermal conductivity ~1000–2200 W/m·K Extremely high
Electrical conductivity Very low Insulating (pure diamond)
Thermal expansion ~1 ×10⁻⁶ /K Extremely low
Melting point Not applicable Sublimates at very high temperature
Magnetism No Non-magnetic
Corrosion resistance Excellent Chemically inert
Machinability Not machinable Requires abrasive or laser processes

Diamond is a crystalline form of carbon, characterized by an extremely rigid cubic structure that gives it the highest mechanical properties known among natural materials. In watchmaking, it is primarily used for its abrasive and cutting properties (synthetic diamond), as well as for its aesthetic qualities in jewelry applications (natural diamond).

Its direct use in watch mechanisms remains very rare and anecdotal, due to its relative brittleness under impact and the constraints associated with its processing. However, it plays a key role in manufacturing processes, particularly in the form of abrasives and cutting tools.

Main Properties

Diamond exhibits exceptional characteristics:

  • Maximum hardness (10 on the Mohs scale)
  • Very high wear resistance
  • Very high Young’s modulus (~1000–1200 GPa)
  • Very high thermal conductivity (~2000 W/m·K)
  • Low thermal expansion coefficient
  • Non-magnetic material
  • Low friction coefficient (high polishability)

These properties make it a reference material for machining and finishing.

1. Natural Diamond

Historically used, particularly in jewelry applications.

2. Synthetic Diamond

Now widely dominant in technical applications.

Production methods:

👉 Enables controlled, homogeneous production tailored to industrial needs (tooling, abrasives)

1. Tooling and Abrasives (Primary Use)

Diamond is used in the form of:

Applications:

  • Component polishing
  • Machining of hard materials (ceramics, synthetic sapphire, carbides, steels, etc.)
  • Finishing of rubies and precision surfaces

👉 Diamond is now essential for achieving the levels of finishing required in watchmaking.

2. Applications in the Movement (Anecdotal Use)

Diamond has been used experimentally or very sparingly for:

  • Bearings
  • Ultra-low friction contact surfaces

Benefits:

  • Extreme reduction of friction
  • Very high wear resistance

Limitations:

  • Brittleness under impact
  • Complex implementation
  • High cost

👉 These applications remain marginal.

3. Jewelry and Setting

Natural diamond is widely used in watchmaking for:

Cut types:

  • Brilliant cut
  • Baguette cut
  • Princess cut
  • Fancy cuts

Setting can be carried out using different techniques:

  • Grain setting
  • Bezel setting
  • Snow setting
  • Invisible setting

👉 Diamond is a key element in jewelry watchmaking.

Advantages

  • Unmatched hardness
  • Exceptional wear resistance
  • Very high precision as an abrasive
  • Prestigious aesthetic
  • Chemical stability
  • Non-magnetic

Limitations

  • Brittleness (possible cleavage)
  • High cost
  • Limited technical applications in movements
  • Sensitivity to shocks