9S Mechanical Caliber

“Our goal was to create the best possible mechanical watch for everyday use.”

This was the vision. Caliber 9S inherits the spirit of the first Grand Seiko from 1960; a timepiece crafted to the same exacting standards as the very best chronometers of its time.
Incorporating both the very latest in watchmaking technology and the finest craftsmanship, Caliber 9S offers high precision and reliability that endures.

The accuracy of a mechanical watch depends greatly on the precision of its hundreds of individual parts. This is why all the components of each Grand Seiko watch are made by Seiko in-house and to the same high standards. To ensure the very highest levels of precision, certain key parts are made using Micro-Electro-Mechanical Systems (‘MEMS’), a cutting-edge manufacturing technology originally developed for semiconductors.

It takes more than a collection of precision parts to make a masterpiece. To reach the strict accuracy standards of Grand Seiko, key parts are individually polished and fine-tuned with great care by elite craftsmen and women to an accuracy of 1/1,000th of a millimeter before being assembled into a complete timepiece.

Seiko is proud of being a true manufacture for over a century. Grand Seiko’s Caliber 9S is the pinnacle of Seiko’s watchmaking today, offering the very best watches for everyday use. The vision is now a reality.

About a mechanism

About a mechanism

The basic principle of the mechanical watch has remained unchanged since the birth of the modern wrist watch. Its enduring charm lies in its compact, self-contained drive system whereby the power comes from the spring alone, without the need for a battery or an electric motor.

A speed control mechanism, known as the “escapement”, plays an important role in guaranteeing accurate time keeping. The escapement comprises escapement wheel and pallet, and maintains the rate at which the mainspring unwinds by using isochronous movement of the hairspring to ensure the hands display the correct time. The escapement also slows the speed of the mainspring so that the watch can run for an extended period.

Hi-Beat 36000

The driving spirit of Hi-Beat 36000


Grand Seiko has been constantly evolving within a culture of traditional watchmaking values.

It may seem contradictory to try and combine continuous evolution with tradition, but for a watchmaker aiming to reach the absolute pinnacle of practical watches, combining these elements is the key to excellence.

In 1968, Seiko introduced a series of three 10 beat (high beat) calibers including the automatic caliber 61GS, the manual winding 45GS and the 19GS for women. Time has shown that Grand Seiko has achieved the highest level of accuracy in the world with high beat calibers.

1968年発売 国産初の自動巻10振動〈61GS〉

More than four decades later, in 2009, Seiko released the new 10 beat caliber 9S85, the most accurate 9S series caliber ever. This was not a revival of 10 beat movements from the past but an entirely original movement with newly developed critical parts including both the hairspring and escapement.

Caliber 9S85: The work of the true manufacturer

A 10 beat caliber beats at ten times a second, or 36,000 times per hour (hence the name “Hi-Beat 36000”). This rate is substantially faster than that of ordinary mechanical movements, most of which beat six to eight times per second, or 21,600 to 28,800 times per hour.

The balance wheel utilizes the isochronism of the hairspring’s pendular motion, controlling the speed at which the mainspring unwinds. It had long been understood in the industry that a faster vibration rate would make the watch more resilient to shock and thus more accurate, but turning this concept into a reality was another story.

The biggest obstacles were running time and durability. Vibrating a hairspring at a higher speed consumes more power from the mainspring, so more torque is required to maintain a power reserve long enough for practical use.

Durability of the escape wheel and pallet also has to be addressed, because together these parts transfer power from the mainspring to the escape wheel, which through regular movement controls the wheel train.

Solving these issues required the development of new materials and even greater precision and durability of many components.

New hairspring material for higher performance

For mechanical movements, the hairspring is the most important component to ensure accurate time keeping.

Seiko has more than 50 years of manufacturing experience and know-how in the making of alloys for springs. In 1964, a new material was created, which was later called “Spron”. Spron is a cobalt-nickel alloy, and it has superior elasticity, great strength, and high heat and corrosion resistance. When the hi-beat development began, the designers decided that a new Spron alloy was needed for the hairspring. It took five years, but the result was worth the wait. The “Spron 610” in the new hairspring was more resilient to shock and magnetism and ensures stable accuracy over time in everyday use.

Sophisticated escapement production process

High beat movements place higher demands on key components, so Seiko used its advanced MEMS manufacturing process for escapement parts. This made it possible for the movement to withstand the higher vibration rate by improving dimensional accuracy and surface smoothness, reducing weight and allowing the shaping of a unique escape wheel tooth which holds the lubricant for longer and thereby increase the efficiency of the escapement.

Mainspring for high speed vibration: stronger torque and longer power reserve

In conjunction with the Institute for Material Research at the renowned Tohoku University, Seiko has been developing and manufacturing its own mainsprings for more than 50 years. Even with all this expertise, however, it took Seiko almost six years to develop a new Spron alloy that had the strength and elasticity required for the new10 beat caliber. The reinforced mainspring meets the 10 beat challenge; with 1.5 times the torque of the existing spring and a power reserve of 55 hours.

Developments on the 9S Caliber.

Caliber 9S86: a 10 beat with GMT function

Launched in 2009, the Hi-Beat 36000 was an immediate and lasting success. In 2014, a new version with a GMT hand was created for the international traveler.

To display GMT, the regular hour, minute and second hands are supplemented with a fourth hand that points to 24-hour marks around the dial, enabling time in two different time zones to be displayed.

The second hand continues to mark time even when the crown is pulled out to the first click to adjust the hour hand to a different time zone, so there is no interruption to the accuracy of the high beat caliber.

Integrating advanced mechanical engineering with craftsmanship for greater accuracy

It is an achievement to make a wrist watch accurate when in a static position, but it is quite another to deliver accuracy when the watch is being worn or otherwise in motion. Typically, mechanical watches demonstrate better accuracy in static positions than when they are worn.

The goal for Grand Seiko was to create a practical mechanical watch that maintains a high degree of accuracy even as the wearer engages in everyday activities. To achieve this, the Grand Seiko team was determined to create a simple, rather than complicated mechanism and deemed it essential that extremely high precision was achieved in the manufacturing, assembly and adjustment of every part.

By adopting new technology for more precise parts and engaging skilled craftsmen to assemble and adjust each intricate movement, Caliber 9S has reached the demanding accuracy benchmark of the “Grand Seiko Standard”.

MEMS technology for high precision parts

Micro-Electro-Mechanical Systems (MEMS) — a highly advanced semiconductor manufacturing technology — is used to fabricate precision parts for Caliber 9S. MEMS technology makes it possible to design and make parts with extreme precision, through the miniaturization of technology that integrates electrical engineering with mechanical manufacturing.

In MEMS production, a design template using electro engineering methods is used, then a nickel plating process is applied. This process of successive plating in a three-dimensional pattern enables the production of extremely precise parts.

The greatest advance in the caliber 9S65 is the high-precision escape wheel and pallet, both manufactured using MEMS technology. By creating new configurations with nickel that are more durable and retain lubricant more effectively, the weight of key components was reduced while power transmission efficiency was improved.

Polishing to perfection

Wheel tooth polishing is just one example of the precision with which every part is processed. To ensure efficient transfer of the critical but limited power of the mainspring, Seiko’s craftsmen and women individually polish grooves between the gear teeth—some of which are as shallow as 6/100th of a millimeter. This painstaking task makes an essential contribution to high accuracy in practical use.

The essence of accuracy

The balance wheel, critical to the accuracy of a mechanical watch, is an incredibly delicate component whose weight is determined to a tolerance of 0.000001 gram.

The accuracy of a mechanical watch is to a large extent determined by the stability of the balance wheel’s revolutions.

Problems arise when the balance wheel subtly deforms due to thermal expansion. To avoid this problem, Caliber 9S uses four arms instead of the usual two or three. This detail increases the work involved in the manufacture of components and is testament to Seiko’s commitment to accuracy.

Spring adjustment

Grand Seiko is a handmade watch. Only the most experienced master craftsmen and women can assemble the several hundred components in each movement. It is the adjustment of the hairspring, however, that demands particular skill and experience.

The beautiful spiral shape of the hairspring is a mere fraction of a millimeter thick, and our craftsmen, using nothing but specially designed tweezers, make the necessary adjustments in the gaps between the spirals entirely by hand.

It’s an operation that is too delicate to be trusted to a machine. Our specialists insist on using the sensitivity of human hands, and the intuition that comes with experience, to achieve a superior adjustment of the balance wheel and ensure precise rotation.

In the words of one of our craftsmen, “If we cut corners here, it wouldn’t be a Grand Seiko.”

These adjustments are not measured by instruments. They rely utterly on the eyes and hands of a select group of craftsmen and women, with a sensitivity honed by years of training and experience. In a world measured by fractions of a millimeter, the accuracy of a Grand Seiko depends on human visual acuity and fingertips more sensitive than even the most advanced technology. This is an exclusive world of craftsmanship, reserved for experts whose skills cannot be replicated by machines.

When adjusting the hairsprings, our craftsmen and women sense the individual qualities of each spring and make minute adjustments to compensate for those unique differences. It is this finely wrought sensitivity that sets Grand Seiko apart. Only when the hairspring forms a beautiful ripple do we see our craftsmen and women smile. That is the moment when the beating heart of the watch – more a piece of art than a manufactured product – is brought to life.

A Passion for Tools

Tools are integral to a master craftsman’s techniques.
True masters work in harmony with their tools, instinctively adapting them to match their habits and adjusting for hand and finger finesse and fatigue.
They could never achieve the same degree of precision without using their own customized tools.

Grand Seiko’s certification and inspection process

In 1960 the first Grand Seiko was born. Each watch was closely inspected and only released if it passed an internal standard equivalent to the leading Chronometer standard of that time.
In 1998, a new and higher Grand Seiko standard was created to coincide with the revival of the mechanical caliber 9S55 for Grand Seiko.

The movement that results from these rigorous inspections is at the heart of Grand Seiko, a watch that truly marks the passage of time.


The Grand Seiko Standard

Grand Seiko’s certification inspection process for the mechanical caliber 9S series takes 17 days. The movement is placed in six positions and is tested at three different temperatures, and its daily variations must fit within the very strict tolerance rates. Once filtered into the case, the watch is tested for a further 21 days.

The Grand Seiko standard differs from the other recognized chronometer standards in two important respects. The Grand Seiko standards tests each watch in six positions, rather than five and at three temperatures rather than two. Why? Because the Grand Seiko tests seek to replicate what happens in real life. The sixth position is the position many people leave their watch when not worn, namely with the 12 o’clock position up right, and the extra temperature rating is closer to the body temperature. The idea is simple; to test the watch under the conditions similar to the actual usage.

testing program & criteria The Grand Seiko standard Chronometer in Switzerland
The establishment year 1998 1951
Mean daily rate +5.0~-3.0 seconds/day +6.0~-4.0 seconds/day
Mean rate variation Less than 1.8 seconds/day Less than 2.0 seconds/day
Maximum rate variation Less than 4.0 seconds/day Less than 5.0 seconds/day
Difference between flat and hanging position +8.0~-6.0 seconds/day +8.0~-6.0 seconds/day
Greatest rate difference Less than 8.0 seconds/day Less than 10.0 seconds/day
First variation of rate per 1℃ (from 38℃ to 8℃) ±0.5 second/day/℃ ±0.6 second/day/℃
Second variation of rate per 1℃ ±0.5 second/day/℃ ±0.6 second/day/℃
Rate resumption ±5.0 seconds/day ±5.0 seconds/day
Number of position 6 5
Temperature 8,23,38℃ 8,23,38℃
Period 17 days 15 days

*Inspection is made prior to casing. Movement performance is carefully measured in the static position under a controlled environment.
*The accuracy of the watch may vary depending on the actual usage conditions and may differ from standard accuracy.
*The guideline for average daily accuracy when worn is +10 sec. to - 1 sec. (9S64, 9S65) and +8 sec. to -1 sec. (9S85, 9S86).

Comparison Chart

Movement Accuracy※1
(in static use)
(in actual use)
Power reserve
(when fully wound)
Jewels 24 hours hand※2
Hi-Beat 36000 GMT
(with manual winding mechanism)
+5~-3 +8~-1 Approximately 55 hours 37
Hi-Beat 36000 GMT
(with manual winding mechanism)
+5~-3 +8~-1 Approximately 55 hours 37  
Automatic 3 days
(with manual winding mechanism)
+5~-3 +10~-1 Approximately 72 hours
(About 3 days)
Automatic 3 days
(with manual winding mechanism)
+5~-3 +10~-1 Approximately 72 hours
(About 3 days)
Manual winding
+5~-3 +10~-1 Approximately 72 hours
(About 3 days)
Automatic 3 days
(with manual winding mechanism)
+5~-3 +10~-1 Approximately 72 hours
(About 3 days)
*1 Accuracy is measured against the Grand Seiko Standard in six positions and under three temperature conditions before casing. Due to the nature of mechanical watches, actual accuracy may differ from standard accuracy depending on conditions of use, including wearing duration, temperature, movement of wearer’s arm, shock and vibration.
*2 GMT (Greenwich Mean Time) function enables the display of two different time zones using the hour hand and a 24-hour hand.