Longines Ultra Chron Cal 431 monoshell case Teal dial

The Longines Ultra-Chron, powered by the Caliber 431, was introduced in 1968 as a high-performance, precision-focused chronometer designed to push the boundaries of timekeeping accuracy. The Caliber 431 was a groundbreaking movement, boasting a high frequency of 36,000 vibrations per hour (vph), which was significantly faster than most other mechanical movements of its time, allowing for improved accuracy. The Ultra-Chron was marketed as the "world's most accurate mechanical watch," and it was tested to meet stringent chronometer standards, ensuring exceptional timekeeping performance. The watch featured a sleek, classic design with a stainless steel case, simple dial markings, and a date function, embodying the elegant yet high-tech ethos of the era. Today, the Longines Ultra-Chron Caliber 431 is considered a milestone in the history of horology, prized by collectors for its technical innovation and vintage appeal.

The one available here today is one with a rather Rare and unique Navy/teal dial with a white details. 

BEZEL MATERIAL
Stainless steel
BRACELET
Leather strap
CALIBER

Cal 431 Serviced

CASE DIMENSIONS

34 mm with 18mm lugs
CASE MATERIAL
stainless steel 
CLASP
buckle
DIAL
teal/ grey/ blue / I am actually colorblind sorry 

GLASS
Plexi crystal,
INDEX
stick
MODEL

Longines Ultra Chron Cal 431

MOVEMENT

Hi beat CAL 431