quattro's meticulous overview of the Omega Calibre 30 I Tourbillon wristwatches offers an invaluable historical deep dive into one of Omega's most significant horological achievements. This article not only details the technical prowess of these observatory trial movements but also traces the fascinating journey of their rediscovery and re-casing, making a decade-old forum discussion relevant to new generations of collectors.
In 1947, Omega created twelve Calibre 30 I tourbillon movements of only 30 mm in diameter to run in the “wristwatch” category of the Geneva, Neûchatel and Kew-Teddington Observatory trials.
In these movements, the tourbillons had a rotation rate of 7.5 minutes as opposed to the more habitual 60 seconds.
These movements did not have a particularly fine aesthetic finish but were technically the best of the best.
Omega’s twelve Calibre 30 I participated in several trials between 1947 and 1952 and, in 1950, the movement with the serial number 10595933 achieved the highest score in the category for a single wristwatch with 867.7 points.
A/ RECORD HOLDER MOVEMENT NO. 10595933 (with disassembled tourbillon cage on the second photo)
In 1987, seven of these twelve movements were discovered by Omega and entirely rebuilt, they were then cased in gold and silver livery and offered to a select group of collectors.
B/ THE SEVEN MOVEMENTS CASED IN 1987
1/ MOVEMENT NO. 10595935 IN A STERLING SILVER CASE
credit: Antiquorum & Christie’s
2/ MOVEMENT NO. 10595936 IN A STERLING SILVER CASE
credit: Antiquorum
3/ MOVEMENT NO. 10595937 IN AN 18k YELLOW GOLD CASE
credit: Antiquorum 4/ MOVEMENT NO. 10595938 IN AN 18k YELLOW GOLD CASE
5/ MOVEMENT NO. 10595941 IN AN 18k YELLOW GOLD CASE
credit: Antiquorum
6/ MOVEMENT NO. 10595942 IN AN 18k YELLOW GOLD CASE
credit: ablogtowatch (1-3) & Hodinkee (4-7)7/ MOVEMENT NO. 10595943 IN AN 18k YELLOW GOLD CASE
credit: Phillips
C/ THE STAINLESS STEEL "PROTOTYPE" CASED IN 1947 Whereas it was always believed that these movements had only been created to participate in Observatory trials (and cased only much later), illustrations and information contained in letters preserved at the Omega Museum showcase plans for a 30 mm tourbillon movement to be housed in a wristwatch.
At least one such wristwatch was created in 1947 featuring a stainless steel case, thus increasing the total count of cal. 30 I to thirteen.
So, the watch shown below is probably the very first tourbillon wristwatch that was supposed to be produced in series.
credit: Hodinkee (here & here)
credit: Sjx 
credit: Phillips
Thanks for reading.
Best, Emmanuel
