'The Speedmaster has remained essentially unchanged for more than half a century and defines the modern chronograph. It is the watch that introduced the tachymetric scale on the bezel; now it is difficult to imagine a chronograph without one,' Urquhart says, noting it was also the first watch worn on the moon.

Other Omega classics include The Seamaster (starting price HK$20,000), an automatic winding chronograph and quartz watch with a stainless steel case and bracelet, screw-in crown and case back, unidirectional bezel and a helium-release valve.

Although Swiss luxury watch manufacturer Patek Philippe has produced many traditional styles, none of its designs articulate timelessness better than the Calatrava line, a collection of classic round wristwatches launched in 1932. Variations and refinements have been made over the years - for example, using ultra-thin cases, updated movements, intricate detailing in the form of hobnail patterns and wide polished bezels - but the collection has remained true to form, showcasing sleek lines and subtle elegance.

'The collection expresses artistic ingenuity at its very finest. The endearing quality of the design reflects the relentless pursuit of perfection that has always been at the core of Patek Philippe's mission,' the brand says.

In fact, classic watch designs are often emblematic of the brand, encapsulating its core values in a single timepiece.

Luc Perramond, CEO of La Montre Hermes, says the brand's Arceau watch (HK$53,100) is a case in point. Designed in 1978, it embodies not only French elegance but also the very essence of the Hermes style. It is distinguished by its upper horseshoe-shaped attachment and slanting numerals across the dial.

Another classic from Hermes is its Clipper watch (HK$43,600), inspired by 19th-century sailing boats and recognised by its porthole-shaped bezel.

'Both product lines are still in the collection and remain pillars. The design has been slightly modernised but the shape has remained a classic. It is an evolution in design, not a revolution,' Perramond says.

A timepiece can be an instant hit or evolve to become a classic over time. Its design ethos will have significant impact on how it is received.

'To a large extent, a classic watch depends on the vision of the designer, how that individual is able to look beyond the taste of people at a particular point in time and come up with something that has unique and lasting appeal,' says David von Gunten, CEO of Audemars Piguet in Hong Kong and China.

For example, Audemars Piguet's Royal Oak steel timepieces, launched in 1972 when the market was still focused on gold watches, took time to be accepted but have since become a classic.

While classic designs remain popular for collectors and wearers, the changing customer profile has prompted watchmakers to update classics.

'Customers are generally getting younger these days as people tend to have more disposable wealth and are becoming successful at a younger age. This group of young clients typically prefers sportier and more contemporary watch designs,' von Gunten says.

That has led watchmakers to retain aspects of classic designs but modernise their look and movements. The Jules Audemars collection did just this by showcasing the movement in a three-dimensional design. One of its watches, which retails for HK$2.2 million, features the Audemars Piguet escapement, a hand-wound chronometer, power reserve indication and a movement of 43,200 vibrations per hour.