Created to celebrate the advent of the new millennium in 2000, reference 5100 combines a groundbreaking 10 days movement with an extremely elegant and intriguing case design deeply rooted in the company’s history.
The 10 days energy reserve is supplied by two massive mainsprings, whose equally massive jewels are well noticeable through the glazed back; this was the first time in the history of watchmaking for a wristwatch to feature a 10 days power reserve. 
The case design is inspired instead by a historical reference: ref. 2442, nicknamed “Manta Ray” as the flared side of the case with the recess for the crown is highly evocative of the enormous fish. In fact, to avoid any misunderstanding regarding the provenance of the inspiration, a picture of the animal is present in the promotional material.
Realized in the three gold colors and platinum, all versions are limited editions: the yellow gold one was made in 1500 pieces, 750 pieces were realized in pink gold, 450 in white gold and production of the platinum version halted at 300 pieces.
Offered by the original owner and fresh to the market, the pieces were sold together by the Patek Philippe boutique in Paris in March 2001. It is most probable that given the importance of the client, Patek Philippe exceptionally issued a group box able to showcase the entire set at the same time: it is the first time that such a set complete with group box appears on the public market.