Case:

Watch cases can be distinguished by material, size and shape.

• Materials (by increasing hardness): Plastic, Brass, Aluminium , Gold, Silver, Platinum, Palladium, Rhodium, Titanium, Steel, Ceramic
• Size: 10-50 mm, gents ø>35 mm, ladies´ ø<30 mm
• Shape: round, square, rectangular, trapezoid, tonneau
• Plating/Coatings: Soft (e.g. brass) or unprecious base materials (e.g. steel) are upgraded by precious (gold) or harder (Titanium) materials. The thickness is measured in micron = µm = 1/1000 mm. Physical procedure with pressure and temperature (PVD - Physical Vapour Deposition) is distinguished from anodizing/acid/electrochemical/galvanic plating.
  Anodized plating are 5-60 Micron thick - the thicker the more wear resistant.
  PVD platings (Cathode atomizer) done with Titanium Nitride, Titanium Carbide or Wolfram Carbide with platinum or gold inlays are up to 20 times harder and more wear resistant, therefore only a thickness of 0.5-2 micron is needed.

Case back:

• Snap-in back costs less, but the max. water resistance achieved is 50 meters.
• Screwed back protect the inside of a watch better against dust and humidity. Can be identified by an outer ring of little notches to set on an opening tool.
• Display or glass backs of mineral or sapphire visualize the mechanical movement. Inside an automatic watch, one can see the rotor.

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