Background
Omega first introduced the co-axial escapement into their serially produced watch movements back in 1999 with the launch of the caliber 2500. The first generation of co-axial caliber was actually adapted from ETA’s workhorse 2892 caliber with specific modifications done to replace the traditional Swiss lever escapement with the co-axial escapement invented by master watchmaker Dr. George Daniels. While the caliber 2500 was revolutionary in its time, Omega faced criticism for having used the widely available ETA movement.
In response Omega launched its effort to develop a brand new in-house caliber incorporating the co-axial escapement. The payoff came in 2007 with the launch of caliber 8500 in the Hour Vision line of watches. Caliber 8500 is the first member of a new family of automatic movements specially designed by Omega to house the co-axial escapement. In its celebration of the 10th Anniversary of the Co-Axial escapement, Omega described the significance of the Caliber 8500 as follows: “For the first time, the company built the entire movement around the Co-Axial Escapement and every one of its 202 parts was developed and produced in-house specifically for the new calibre.”
2 years after the launch of the Hour Vision watches, the new Seamaster Aqua Terra from Omega was announced in February 2009. The latest incarnation of the Aqua Terra line not only sports a brand new look and dial but ticking inside is Omega’s in-house co-axial caliber 8500.
Overview of the watch
The Aqua Terra is a chronometer grade self winding 3 hand watch featuring hour, minute and central seconds with date feature.
The following specifications are taken from the Omega website:
REFERENCE: 231.10.42.21.06.001
MOVEMENT: Omega Co-Axial Caliber 8500 ; Self-winding movement with Co-Axial Escapement for greater precision stability and durability. Free sprung-balance, 2 barrels mounted in series, automatic winding in both directions to reduce winding time. Visible bridges and the oscillating mass are decorated with exclusive Geneva waves in arabesque. Power Reserve: 60 hours
CRYSTAL: Domed scratch-resistant sapphire crystal with anti-reflective treatment on both sides
CASE: Stainless steel case
DIAL: Teck-grey dial
WATER RESISTANCE: Down to: 150 meters/500 feet
CASE DIAMETER: 41.5 mm
Omega Co-Axial Caliber 8500
Caliber 8500 – note the DLC coated twin barrels which supply 60 hours power reserve
Image source: Omega
Unlike the older Aqua Terra watches which were equipped with the caliber 2500, the new Aqua Terra models have been upgraded with Omega’s in house caliber 8500. While the caliber 2500 is basically an ETA 2892 derivative, modified to fit a co-axial escapement, the new caliber 8500 is Omega’s exclusive in house movement designed from the ground up to fit the Co-axial escapement.
The Co-Axial escapement was invented by the English master watchmaker Dr. George Daniels, to replace the traditional Swiss lever escapement found in virtually all modern mechanical watch movements. The revolutionary design of the co-axial escapement drastically reduces the sliding friction component of the escapement. This theoretically results in less need for lubrication, longer service intervals and greater accuracy over time.
The new caliber 8500 found in the Aqua Terra also feature a hairspring made of Si 14, which is non-magnetic, more shock resistant and has improved isochronism. The other component made of silicon is the balance wheel, further increasing the movement’s resistance to the influence of magnetic fields. (Correction: The calibre 8500 is not equipped with silicium hairspring and balance wheel.)
Other notable features of the caliber 8500 include:
- Dual mainspring barrels to increase the power reserve to 60 hours.
- Free sprung balance which improves on the isochronous quality of the watch by eliminating the need for a regulator.
- Balance bridge instead of balance cock for improved stability.
- Bi-directional auto winding mechanism for better winding efficiency
- Independently adjustable hour hand to facilitate time adjustment when crossing different time zones.
- C.O.S.C. certified chronometer.
Caliber 8500 Technical Specifications:
Brand: Omega
Model: Caliber 8500
Description: Mechanical movement with co-axial escapement, automatic winding
25’200 vibrations per hour (3.5 Hz)
39 jewels
Diameter: 29.0 mm (13 lignes)
Thickness: 5.50 mm
Functions: hours, minutes, seconds and date window
Power reserve: 60 hours
Shock absorption: Nivachoc
As the photos below show, the movement finishing is very nicely executed. The plates are decorated with circular graining or perlage pattern and the visible bridges and rotor are finished with exclusive Geneva waves in arabesque decoration.
View of the screw down display case back with sapphire crystal
The excellent finish on the bridges and rotor- cotes de geneve in arabesque
Case
The case is 41.5mm in diameter (without crown) and approximately 12.5mm thick. Lug to lug the watch measures 49mm. The stainless steel case has a mix of polished surfaces and brushed finish. The lugs are Omega’s signature lyre lugs. Around the crystal is the elegantly polished bezel ring which really adds to the Aqua Terra’s appeal as a dress watch. The screwed-in case back comes with a display glass which gives a clear view of the beautifully decorated caliber 8500. The watch is rated to 150 meters water resistance.
The dart shaped index, hour, minute and second hands are coated with white Super Luminova.
Crystal
The watch is equipped with scratch resistant sapphire crystal on the front and back. The front sapphire crystal is curved and coated with Anti reflective layers on both sides of the crystal.
Dial & Hands
The “Teck concept” dial – inspired by the deck of a luxury boat.
Image source: Omega
The dial is dark grey in color and has a unique vertical design pattern which is clearly inspired by the wooden decks found on luxury boats . Circling the dial are elegantly finished metallic applied index markers which are dart shaped. There is an outer ring lined with the minute markers and arabic numeral indicating 5 minute increments. The Omega logo and name together with the Seamaster insignia are printed legibly below the twelve o’clock position. A date aperture is located at the three o’clock position. The date disc has black background with printed white numerals. The date window is equipped with a nicely finished metallic frame. The labels Co-Axial, Chronometer and 150m are printed above the six o’clock position, to indicate that the movement has been equipped with a co-axial escapement with official COSC chronometer rating and the watch case is water resistant to 150m. Below that is the finely printed “Swiss Made” label.
The hour, minute and second hands are rightly proportioned. The signature arrow head and spear head adorn the minute and second hands respectively. These small details allow the different hands to be differentiated easily at a glance which really adds to the overall legibility of the watch.
Note the elegantly framed date window and the white date numerals on black date disc.
The signature arrow head on the minute hand and the spear head on the seconds hand.
Nicely done Omega logo.
Crown
The crown is screw down type for improved water resistance, and is signed with a fairly large Omega logo.
Beautifully signed screw down crown.
Bracelet
The watch comes with a very well designed metal bracelet with solid centre links and end links. The bracelet is solidly constructed yet very comfortable to wear. Unlike the older bracelet design which utilizes friction pins, the new Aqua Terra bracelet is equipped threaded link pins. The buckle is the deployant type and is signed with the Omega logo.
Signed deployant buckel, solid centre links and end links make up the top notch bracelet.
Deployant buckle with two button release and the new threaded links.
Lugs
The watch case comes with the signature lyre lugs seen on many of Omega’s more popular models. The lugs are finished smoothly with no sharp edges. The lug width accommodate 20 mm size straps which are attached using spring bars.
Conclusion
The new Aqua Terra is a dress watch equipped with an excellent chronometer grade Co-axial movement. Not only is the new caliber manufactured in-house by Omega, it is also equipped with the silicon hairspring which provides excellent shock resistant and anti magnetic properties. The watch is attractively designed and solidly constructed. With the new Aqua Terra watches, Omega has presented to the market a product which provides excellent value and will definitely give the Rolex Datejust a run for their money. The challenge issued by Omega has not taken lightly by Rolex as clearly shown by the release of the 41mm diameter Datejust II models. When competition intensifies between these giants of the industry, it will inevitably spur evolutionary improvements in their long established product lines & the only winner will be the consumer.
Resources:
i) Seamaster Aqua Terra – link to Omega information page
ii) Co-axial Caliber 8500 – Omega press release
iii) Omega presentation – 10 years of Omega’s Co-axial Escapement
iv) Pre-Basel 2009 Press Release on New Seamaster Aqua Terra
v) Omega’s presentation on how the Daniels Co-Axial Escapement works
As far as I know this model does not have a Si14 spring. Only the annual calendar model has it.
Let me know if I am right, thanks
Gabor
Hi Gabor,
You are right. I stand corrected. Thanks for the heads up.
Thanks for the nice review! I actually wrote a review of mine compared to the Rolex Datejust on watchuseek. I come to the same conclusion as you do.
As far as I know, the Annual Calendar, as you say, has the silicon spring, as well as the Ladies’ model and also the Deville Hour Vision. I think they wanted to first try it out on models that will sell less, if anything goes wrong, as was the case with the 2500 movement where there were quite a lot of hiccups.
7 Hz.
Not 3.5, as 25,200/3,600 = 7.
Hi Sterling,
My understanding is that a beat or vibration of the balance wheel represents its swing in one direction. A full oscillation or cycle of the balance wheel is represented by 2 beats or vibrations of the balance wheel. Hence a movement that beats at 25,200VPH/BPH equals 12,600 oscillations per hour which in turn equals 3.5Hz.
Can u elaborate on power reserve. What does 60 hrs mean. I bought a watch in last June & find watch slows down if do not wear for than 24 hours. Appreciate comments .
Hasan
Power Reserve of 60 hours means that the watch, after it has been fully wound, can be expected to keep operating for 60 hours if left on its own without user intervention. A basic mechanical watch usually has a power reserve of 38 to 48 hours. 24 hours is a little short, but you would want to verify that the watch was fully wound before being left unworn.
Hi Danny,
Thanks for the excellent review. The photos you used were fantastic; it looks artistic. I recently bought myself this watch and I can attest to how beautiful it is.
Andrew.
Hi Andrew,
Thank you for the kind words. I’m glad you like the review.
The Omega Seamaster Aqua Terra is a beautifully designed watch. To me the watch’s appeal is enhanced exponentially when you factor in Omega’s in-house caliber 8500 with co-axial escapement.
You certainly made the right choice in acquiring one for yourself.
Wear it in good health.
Hi Danny,
Are you absolutely positive the Si 14 balance spring and balance are NOT fitted on the calibre 8500 of this version (date only Aqua Terra)? I was really looking forward to this specific model. If they upgrade the movement with the silicon parts, and I send it in for servicing, do you think they will replace the movement with the new silicone one (?).
nvm… just checked their site. Only the month and date version has it. I find that silly. Perhaps they will outfit it later.
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Regarding Si14, pure Silicon is a good conductor of heat and very brittle and prone to chipping. The method to make a pure silicon hairspring uses Deep reactive-ion etching (DRIE) and is expensive to do for large parts like a hairsprings. due to the potential brittleness of such a silicone spring I would not consider this a plus on a watch I wanted to wear everyday. There really is no point to such a part. The ETA 2824s are easily serviced and once calibrated not hard to get +4 -2 seconds a day or better. I have gotten such calibrations out of the cheap China movements as well with a bit of patience and once they wear out just replace them as they are not easy to rebuild them.