Watch Terms Glossary

The outside of the watch

• Case: the body of the watch that holds the movement
• Bezel: the ring around the crystal; it may rotate for timing or a second time zone
• Crown: the knob used to set the time and wind the watch; a screw-down crown seals better against water
• Lugs: the horns that attach the strap or bracelet to the case
• Lug width: the space between the lugs, which tells you which straps fit (for example 20 mm)
• Crystal: the clear cover over the dial; sapphire is very scratch-resistant, mineral and acrylic are softer
• Caseback: the back of the case; an exhibition caseback has a window to see the movement

The dial

• Indices (markers): the hour markers on the dial
• Lume: luminous material, such as Super-LumiNova, that glows in the dark
• Sub-dial (register): a small dial within the main dial, common on chronographs
• Cyclops: the magnifier over a date window

The movement

• Movement (caliber): the engine of the watch
• In-house: a movement designed and made by the brand itself
• Power reserve: how long a fully wound watch runs, often 38 to 80 hours
• Jewels: synthetic rubies used as low-friction bearings
• Beats per hour (vph): how fast the balance oscillates; 28,800 vph (4 Hz) is common
• COSC / chronometer: a watch certified by Switzerland's official chronometer testing institute for accuracy

Water resistance, in real life

Ratings are measured in a lab, so treat them as a guide:

• 30m (3 ATM): splashes and rain, not swimming
• 50m (5 ATM): brief swimming
• 100m (10 ATM): swimming and snorkeling
• 200m and up: diving

Buying terms

• Full set: the watch with its original box, papers and accessories
• Reference (ref.): the model number that identifies a specific version
• NOS (new old stock): an older watch that was never sold or worn
• Grey market: new watches sold outside the brand's authorized dealer network