Urban Jürgensen ref. 11CR

PROTOTYPE N°012 Pivoted Detent Escapement

Chronometer COSC certified

In 2003, Urban Jürgensen owner and watchmaker Peter Baumberger together with the brand’s master watchmaker Derek Pratt started to develop for the first time in watch history a serial produced detent escapement for a wristwatch. Sadly master Pratt, close friend of George Daniels whom he helped with the Co-Axial escapement research, passed away never to see his 21st century innovation come into production.


A few years into the research process, young engineer Jean-François Mojon, director at IWC who had just founded his own R&D Company, was mandated to develop Urban Jürgensen’s first in-house caliber. This future P8 caliber would have to integrate the new detent escapement.


Soon another master watchmaker named Kari Voutilainen joined the team and took charge of the high grade finishing, casing and regulation of the new movements. As well the initial production of guilloche dials were remarkably hand-engine turned in Kari Voutilainen's atelier.


The whole project matched perfectly the brands historical philosophy of best talent strategy as one must admit this impressive team of specialists certainly adds enormous desirability to these Prototypes. Peter Baumberger, a scrupulous designer and talented watchmaker himself, had an eye to discover and engage specific talents for his brand.

The prototype of the new caliber P8 with its patented chronometer escapement and safety system was introduced in Basel fair 2011. The same year the Urban Jürgensen P8 caliber won first prize for best innovation at the reputable SIAR Mexico fair. Another important award was achieved in 2014 when the UJS Ref 11C SC Rose gold (Central Second version) received the first prize in the GPHG Men’s category.

According to the UJS archives, of about 40 finished prototypes, 15 were cased in rose gold, 13 in platinum and 12 in steel.

They were not intended for official sale but fully assembled for testing purposes.


Ref. 11 CR n°12 is a rare pink gold cased prototype dressed with a superb hand-guilloché silver dial.


This timepiece is certainly a connoisseur’s choice and a great addition to every high-class watch collection.​


I welcome and will respond to your request on my address: info@watchcollector.lu



UJS caliber P8 (Prototype signed N°012, circa 2011)

Pivoted Detent Escapement

Manual wind mechanism

Regulated in five positions, heat/cold/isochronism

D = 32 mm

H = 5.25 mm

Twin barrel “in series”

88 hours power reserve

21600vph (3Hz)

Large free sprung balance, diameter 12 mm, 24g/cm2

Patented differential mechanism for power reserve indication

Patented Pivoted detent escapement with safety system, US Pat. N° 7458717

Stop second (hack feature)

Optimized teeth shape to reduce friction

25 jewels

Highly finished rhodium plated with sunray decoration



18K Rose gold (5N)

Round tripartite case with soldered teardrop lugs and rounded case band profile

Screwed sapphire back

D = 42 mm

H = 12 mm

Water resistant: 30 meter


Guilloché-main at the atelier of Kari Voutilainen


Urban Jürgensen reference 3

Very early pink gold N°010

NOS, never worn, box, certificat and booklet

This is a rare opportunity for every high-class collector to own a very early, legendary Urban Jürgensen reference 3. It comes in NOS condition, never been worn with box, certificat and booklet. The combination of the early production number and the fact that this examples never has spent time on a wrist is a unique chance for every connaisseur of independent watchmaking.

In the 1990s, when the reference 3 was presented, Urban Jürgensen was guided by Peter Baumberger and together with Derek Pratt they developed their collections. Derek Pratt was as well the one who developed the up/down mechanism on the reference 3 (image of the mechanism in the gallery), which took almost 2 years of research, different technical drawings and three dozens of additional parts to finally fit into the ultra thin (2.4mm) Frédérique Piguet base movement. The more, the whole modification for the perpetual calendar indication was as well developed and produced in-house at the atelier of Urban Jürgensen!


To finish the guilloché dial, it takes more than 700 operations and 2 days of work. The moon display requires over 20 operations to produce the blued steel background with inserted gold moon discs and stars that are punched in one by one. The effort required to produce the elegantly curved springs and levers of the perpetual calendar mechanism is partially unlimited. Each steel surface is carefully grained and the edges angled and polished to perfection (photo of the perpetual calendar mechanism in the gallery). The tear drop lugs are individually forged and then soldered by hand to the case. 


The level of finissage on the Urban Jürgensen reference 3 timepieces is at the very highest standards of watchmaking.

This timepiece is certainly a connoisseur’s choice and a great addition to every high-class watch collection.​


I welcome and will respond to your request on my address: info@watchcollector.lu



Base Automatic caliber FP71, 18 000 vph

In-house modified by Derek Pratt

Perpetual calendar mechanism

Power reserve indication mechanism

Guilloché-main 21kt gold rotor

40 jewels, 2.4mm high


18kt rose gold

38mm diameter

Each single lug forged and welded to the case

Solid caseback


Guilloché-main by Derek Pratt N°010


Patek Philippe 2584

12-600AT movement, 36mm case, NOS

Only 2 known with black épargne dial!



To find one of these reference 2584 in NOS condition is almost impossible and in combination with black épargne dial by Cadran Stern it is a really rare timepiece. The reference 2584 is powered by the legendary 12-600AT movement and comes in a case of 36mm.


The present example is simply amazing. Only 2 yellow gold with black épargne dial watches do exist and this is the only one in truly NOS condition, as you can see from the images. A spectacular watch  The dial is made by Cadran Stern with the complicated "épargne" technique, which means that first the base plate is gilted, then the signature, minuterie and small seconds are protected by a special lacquer, after that the dial is colored in a black galvanique bath. After the black color has dried, the protective lacquer is taken off. Later the hour baton indexes and the 12 o'clock indexes are added.

This timepiece is certainly a connoisseur’s choice and a great addition to every high-class watch collection.​


I welcome and will respond to your request on my address: info@watchcollector.lu



Automatic caliber 12-600AT, 30 jewels

12 lignes, 27mm wide. 6mm high

18kt yellow gold guilloché rotor

Gyromax balance wheel, 19800 vph

Swan neck regulator and self compensating Breguet balance spring

Adjusted to 5 positions, heat and cold, and isochronism



18kt yellow gold

36mm diameter


Black épargne by Cadran Stern

Audemars Piguet A-series

Full spec

When it comes to watches that every high class collector should have in its collection then the legendary Patek Philippe 3700/1 and Audemars Piguet 5402ST-A Series are usually on the list too.

Both are designed by Gerald Genta, the 5402-A in 1972 and the 3700/1 in 1976. The case designs show both an octagon form, which is still present on the modern versions of these two references. But for me, the epitome is always the beginning, the first ones, the 5402-A and 3700/1.

One of the most interesting design parts on the two watches is the dial. The design was developed by Cadran Stern, Roland Tille who was back then the master developer at cadran stern. Gérald Genta approached Roland Tille in 1972 to develope a design for the dial of the Audemars Piguet 5402ST. Roland Tille then used the newly developed method of "tapisserie" to create 13 examples of different designs and Audemars chose the one design that is still in the DNA of the Royal Oak today. The A-series has a tapisserie finissage, black galvanic dial with a protective layer of lacquer on it.

The idea to create this design with the technique of "tapisserie" originates of a dial that Roland Tille created in 1971 for Movado, their St. Christopher model. As Roland Tille said, the design of this dial for Movado resulted in the development of the "tapisserie" technique and so into the legendary design of the 5402ST and 3700/1 dial design!

This A-series is certainly a great addition for every high-class collector. It comes as full spec with its original bracelet, clasp, "AP" links, original crown, a superbly preserved dial and a strong case.


I welcome and will respond to your request on my address: info@watchcollector.lu



Automatic caliber 2121, base Jaeger LeCoulter 920

21600 vph

36 jewels

28.40mm diameter, 3.05mm high


Stainless steel

39mm diameter


Tapisserie by Cadran Stern

Black galvanique with protective layer of lacquer

6*2452 on the back of dial

6 for AP

* for Cadran Stern

2452 for the order number