Sotheby's will offer an extremely rare items from Patek Philippe on October 8 in Hong Kong as part of its Important Watches Autumn Sale, with a monumental and unique clock watch set to star.

Unique pieces from Patek Philippe are reserved for the most prestigious clients, and are snapped up at auction

The clock watch was made to order in the 1980s, as part of Patek's limited series of Grand Complication pocket watches, each of which was unique and made using traditional techniques.

Boasting decoration by the world-renowned enamellist G Menni, it features a portrait of the client's daughter and son, and is a superb example of the "time-consuming and exacting art" of enamelling. It is expected to sell for $590,000-710,000.

The clock watch is joined by a "super impressive" platinum and diamond wristwatch with cathedral gongs, moon-phases and leap year indication. Made circa 2011,  Reference 5073 was made in limited numbers due to the limitations of the company's minute repeaters versus a platinum and diamond-set case.

The watch is valued at $620,000-710,000.

Greubel Forsey specialises in new inventions that aim to improve timekeeping precision even further

Further highlights of the sale include a Greubel Forsey Tourbillon 24 Secondes Comtemporain "Royal Blue", which was developed to showcase the 24-second tourbillion. The watch offers a three dimensional visual experience, with the tourbillon bridge made of transparent sapphire and showing the regulator floating in midair.

Only 33 examples of the watch were ever made, each engraved with the philosophy of independent watchmakes Robert Greubel and Stephen Forsey. Comprising 88 parts that weigh just 0.39 grams, it is expected to see between $230,000 and $320,000.

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