Although Swiss, American, and Japanese companies developed and introduced quartz watch movements at the same time, the Swiss were slow to improve on their first designs. By the mid-1970s, Japanese companies were pulling ahead with thin, reliable quartz movements, while the Swiss were just developing their second-generation technology. This translated into sales, especially in America and Asia, and threatened the Swiss watch industry.
American businessman Gerry Grinberg demanded that the Ebauches SA and their subsidiary ESA/ETA develop a world-beating ultra-thin movement before they lost the entire market to the Japanese. Grinberg had made a fortune building Piaget into a powerhouse for ultra-thin luxury watches but watched that market evaporate as Seiko and Citizen pushed quartz thinner than any mechanical movement. He offered CHF 2 million if ESA/ETA could deliver an ultra-thin 9 ligne quartz movement for use in a new line for his Concord watch brand.
On January 12, 1979, at press conferences around the world, Ebauches SA and ETA, together with Concord, Eterna, IWC, and Longines announced the world's thinnest watch. Measuring just 1.98 mm thick, the three manufacturers introduced remarkably similar watches. All were powered by the ESA Cal. 999, a thin watch movement built directly into the rectangular watch case. It had been developed in under 2 years and was built by Ebauches SA for all three brands. It was so thin it required the world's smallest battery; developed by ETA subsidiary Renata, Battery No. 32 measured just 6.8 mm diameter in 1.1 mm thick. The watch lacked a crown, using a push on the caseback to set the time and change the timezone.
The watch was branded Delirium, and this is the name used by Concord for their models, which were focused on the American market. Eterna called their version the Espada while IWC and Longines simply used the name, Quartz. Eterna and Longines also sold the Ladies model, called Delirium 2 by Ebauches SA, Linea III by Eterna, and Delirium III by Concord. The watch was extremely expensive and impractical, selling for over CHF 10,000, but showed the world that the Swiss could compete directly with the Japanese.
ETA used the Delirium technology as the basis for the Swatch, introduced on March 1, 1983. That project was initially known as “Delirium Vulgare” (“Delirium for the masses”) with the movement similarly constructed directly into the back of the case. This would be the most lasting legacy for the Delirium project. Lead by the legendary ETA CEO Ernst Thomke, a small team of engineers (including Elmar Mock and Jacques Müller) and marketing consultant Franz Sprecher conceived of an inexpensive plastic quartz watch with fashionable colors and designs. Although the Delirium design was quite different from the Swatch, the former lead directly to the latter.
ETA also used the basic Delirium design to produce a standalone movement measuring just 0.98 mm thick. Longines used this as part of their Collections XL line in 1983. After this, only Concord continued to used the Delirium name. Today, Delirium is a line of moderately-thin watches for Concord.
The original Concord Delirium (later named Delirium I) was launched in January, 1979. It measured just 1.98 mm thick overall and had a rectangular case measuring 24.50 mm across and 29.60 mm lug-to-lug. The synthetic sapphire crystal was 0.28 mm thick.
This entire watch was produced by Ebauches SA with assistance from ETA, which referred to the watch as Cal. 999.001. It was sold by Concord, Eterna, and Longines under the names Concord Delirium, Eterna Espada, and Longines Quartz. IWC also offered this model as their Ref. 3000 IWC Quartz.
In June or July 1979, Ebauches SA announced another Delirium model that measured just 1.43 or 1.44 mm thick. Due to the ultra-thin design, it was intended only for collectors. ETA manufactured the entire watch, referring to it as Cal. 999.301.
Eterna marketed this as the Linea Quartz Skeleton while Concord called it the Delirium II.
A model for ladies was released in January 1980. The Ladies model was released less than a year after the original, which it strongly resembled. It measured just 1.68 mm thick and had a rectangular case 20 mm wide and 23.6 mm tall. The synthetic sapphire glass measured just 0.21 mm thick and the 1.1 mm battery provided 18 months of runtime. ETA manufactured the entire watch as well, referring to it as Cal. 999.401.
This model was also marketed by Concord (as the Delirium III), Eterna (as the Linea III), and Longines (as the Delirium 2).
The Delirium IV was introduced in December, 1980. At just 0.98 mm thick, it remains the thinnest watch ever produced. Rather than hands, these watches featured revolving sapphire discs engraved with a line, which were inset into the dial. The sapphire crystal measures just 0.19 mm thick, and the special battery, produced by Renata is just 0.80 mm thick. This was also offered by Eterna in April 1980 as the Linea Museum Watch.
Concord introduced the Delirium Mariner in 1981. Although thicker than any previous model at 2.58 mm, it was nevertheless an extremely thin watch. This added thickness allowed it to be water resistant to 2 atmospheres. It featured “ribbed” styling reminiscent of the hit Piaget Polo model and an integrated bracelet that appeared continuous from the wrist around the bezel. The Delirium Mariner lacks a crown like other previous Delirium models.
The later Concord Mariner and Mariner SG line were un-related. They did not use the original Delirium movement and added a crown. It was also thicker, though still a very thin watch. Most Mariner models used a 12-sided bezel on an integrated bracelet case similar to the Royal Oak.
The Delirium La Scala collection from Concord were paved with diamonds and set in precious metal cases.
In 1983, ESA created Cal. 999.331, a combo movement with both analog hands and a digital readout. The movement included four photocells at the base which could be used as controls for the integrated microcomputer. The resulting watch was just 2.98 mm thick.
In 1988, Concord refreshed the Delirium line with a conventional crown. Now using a standalone 1.0 mm movement, the new Delirium measured 2.95 mm thick. It was a much more conventional watch, sturdy enough for daily wear, resistant to water to 2 atmospheres, and available in steel or gold with a variety of bracelets and straps. Notably, this new model included a crown for adjusting the time, something not seen on previous models.
The Delirium Spica was a platinum and diamond version introduced in 1990. In 1992 at BASEL, Concord showed a new version of the Delirium with a date complication. The movement, still measuring just 0.98 mm thick, was the thinnest quartz date movement ever made.
In 2005, Concord introduced a mechanical Delirium model, much thicker than the original but retaining the rectangular case.