Horology sounds dirty. But actually it’s the art of making watches, and nobody knows what makes them tick better than Phil Duffell, the manager of Cellini Jewelers in New York’s Waldorf-Astoria Hotel. Here are a few of his favourite features.

1. Tachymetre

A scale, inscribed around the watch’s rim, measures speed – either yours or that of an object you’re watching. A quality watch doesn’t just tell time. It says a lot about a man

Related: How to Buy Your First Watch

2. Chronograph

This simply means it has a built-in 12-hour stopwatch.

3. Display back

The transparent crystal on the back reveals the innards of the timepiece. It’s not useful, but it scores high in the cool stakes.

Related: 5 Questions To Ask Before Investing In That New Watch

4. Slide rule

There’s an analogue calculator on the face of the watch, enabling you to do multiplication, division and metric conversions.

5. Dual time zone

The second time zone, convenient for business travellers, is displayed in a much smaller window