Watch Terms: The Quick Reference Card

Quick Reference Card

A printable reference for the most common watch terms and their meanings. Keep this handy.

Movement Terms

• NH35: Seiko automatic, 3-hand date, 21,600 vph, 41h reserve
• NH34: Seiko automatic, GMT (4th hand), same base specs
• VK63: Seiko mecha-quartz chronograph
• Beat rate: oscillation frequency — 21,600 or 28,800 vph
• Power reserve: how long the watch runs after full wind

Case Terms

• Lug-to-lug: total height from tip to tip — the most important fit measurement
• Diameter: width across the dial — the most quoted size
• Thickness: height from caseback to crystal top

Water Resistance

• 3ATM: splash-proof only
• 5ATM: brief swimming OK
• 10ATM: swimming, snorkeling
• 20ATM: diving rated

Quality Terms

• Applied indices: physical markers — premium over printed
• AR coating: anti-reflective — improves clarity
• Screw-down crown: compresses gasket for water resistance

Frequently Asked Questions

What does COSC mean?
Swiss accuracy certification — -4/+6 sec/day. See our COSC guide.

What is PVD?
Physical vapor deposition — case coating for color and scratch resistance. See our coating guide.