Cartier Ballon Bleu Silvered Opaline Dial Ladies Watch WJBB0002

Ref. 198'095 is one of only four Patek Philippe minute-repeater wristwatches from the Graves collection, two of which are on display in the company's museum. The third was sold at Sotheby's in New York in 2012 for 2,994,500 US dollars, which was five times its lowest estimate. The fact that this is the only remaining piece available, and the only known one with a platinum cushion case, explains the astronomical estimate of 1.2-1.8 million Swiss francs for this piece at the Christie's sale on Monday.

Patek Philippe is also the star of the Sotheby's and Antiquorum sales, headed up in both cases by minute-repeaters with retrograde perpetual calendars in platinum: a Ref. 5013P in the former (with an estimate of 380,000-580,000 Swiss francs) and a Ref. 5016 in the latter (600,000-800,000 Swiss francs).

Rolex is well represented in all three sales with, among many others, two highly sought-after pieces in the Antiquorum sale: a 1964 Ref. 5513 Submariner with rare Arabic numerals on the dial (estimate 80,000-100,000 Swiss francs) and a Ref. 6202 "Monometer", of which only five examples have appeared on the market over the past 20 years. A rare Greubel-Forsey Invention Piece No. 3, one of only 11 made, is also worthy of note, with an estimate of 200,000-300,000 Swiss francs.

The only other name that would appear to be able to hold a candle to Patek Philippe in terms of valuations is Breguet, with a No. 1176 in the Christie's sale expected to fetch between 600,000 and 1 million Swiss francs and a No. 2783 between 200,000 and 400,000 Swiss francs.

A browse through the Christie's sale catalogue shows the gulf in prices between what is deemed collectible and what is less so. A handful of Patek Philippe pocket watches, for instance, appear to be a steal with estimates under 5,000 Swiss francs, compared with in excess of 20,000 for pocket watches by Vacheron Constantin in the Sotheby's sale.

Worldtempus quizzed Geoffroy Ader, European Head of Watches for Sotheby's, on this wide gulf in prices. "If you look at the market, there are two different types of collection fields in the wristwatch area," he explains. "There are what I call the star brands, which are manufactures like Patek Philippe or the sports watch par excellence, which is Rolex. But then you also have the star models, which are as popular as the brand if not more popular, like the Royal Oak by Audemars Piguet, the Reverso by Jaeger-LeCoultre, the Type XX by Breguet and models like this. So it is always difficult to make a judgement based only on the brand. There are collectors for every single brand; it is just that you have some brands that make bigger results than others and obviously people look at the results."

Sotheby's is also offering the more eclectic mix in its sale, including automata and music boxes from the personal collection of Jacqueline Reuge of the family of famous music box manufacturers. "One of my favourites is a small ring by Cartier, which has a LeCoultre movement, calibre 101, which is a masterpiece of Art Deco," admits Geoffroy Ader.

But it is, unsurprisingly, another of Mr Ader's favourites, a Rolex Daytona with a so-called "panda" dial that promises to be one of the stars of the show. Besides the appeal of the model itself, this particular lot will be a magnet for collectors because of its condition. "It comes with the original box and all the accessories," says Geoffroy Ader. "The condition is almost as if you were buying the watch new in the shop 40 years ago."

Antiquorum Important Modern & Vintage Timepieces
11 May 2014, 11am CEST
Mandarin Oriental Hotel
Quai Turrettini 1, Geneva

Christie's Important Watches including Property from an Important European Collection
12 May 2014, 10am CEST
8, Place de la Taconnerie, Geneva

Sotheby's Important Watches
14 May 2014, 10am CEST, Geneva
13, Quai du Mont Blanc