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Old 24 November 2023, 09:43 AM   #1
168000
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Cosc evolution

Looking at my Rolexes, they all are cosc but they are from 3 different era:

- 168000 from 1988
- 16470 from 2011
- 116520 from 2015

I am therefore wondering if the cosc specs have evolved over time and if the 3 of them have the same accuracy.

I have quickly checked the cosc website but could not find anything.

Any idea guys?
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Old 24 November 2023, 12:05 PM   #2
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COSC is a certification process to be called a chronometer per Swiss law; it is independent and not affiliated with Rolex.

COSC was instituted in about 1974 and the criteria for testing and passing this chronometer certification has remained the same.

Being certified a Chronometer has little to do with the accuracy of your watch, only that it passed a test where it performed within the criteria. Once tested and passed, a watch is never tested again.
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Old 24 November 2023, 12:46 PM   #3
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Thanks for the answer! It is exactly what I was looking for.
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Old 21 December 2023, 12:13 PM   #4
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Just for a little more clarity.
The watch isn't tested as an assembly.
Only the movement is tested and it's not cased up(in the watch).
The movement alone is tested in a sequence of 5 positions across 3 temperatures for about 14(i think from memory) days.

Very happy for someone to fill in any blanks or correct any errors.
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Old 21 December 2023, 06:44 PM   #5
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Quote:
Originally Posted by Dirt View Post
Just for a little more clarity.
The watch isn't tested as an assembly.
Only the movement is tested and it's not cased up(in the watch).
The movement alone is tested in a sequence of 5 positions across 3 temperatures for about 14(i think from memory) days.

Very happy for someone to fill in any blanks or correct any errors.
15 days they are tested the COSC and it was started in 1973 by the Swiss and for only Swiss made watches.And just like any test results are for time of testing on whatever machine used.And even tested watches can go out of spec, so its not a 100% guarantee it will perform exactly the same every day, only the fact its been tested and passed at time of testing.
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Old 22 December 2023, 07:31 AM   #6
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Thank you for tidying that up Peter

I thought the test was about 2 weeks straight
It's a funny number with it being 15 days
I do wonder how they came up with the sequence of the test.
The positional variation is pretty much a given, but the duration and temp variations(which sort of make sense) could've been any combination?
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Old 22 December 2023, 06:54 PM   #7
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Thank you for tidying that up Peter

I thought the test was about 2 weeks straight
It's a funny number with it being 15 days
I do wonder how they came up with the sequence of the test.
The positional variation is pretty much a given, but the duration and temp variations(which sort of make sense) could've been any combination?
Yes its only the bare uncased movement that sent to the COSC for testing not even dial hands or winding rotor are on movement.And for movements of Rolex size its costs around $140 plus for each movement test.But as Rolex is the biggest tester they and have there own machine to test the vast amount of movements expect they get a much better deal.And its a good job some of todays Rolex owners cannot see how the movements are tested at the Swiss COSC,on the 15 day environment controlled test they only tests movements at their barest functional level.And all the bare uncased movements are machine wound hundreds at a time by the winding stem.All automatic watches have there winding rotors removed,because the machine that winds them that fast it would damage the highly geared automatic winding mechanism.Even the dial and hands are removed special ones are fitted at COSC test centre. Movements are checked every 24 hours by electronic camera linked to central computer. These bare movements are loaded into magazines like bullets,the machine extracts the movement, reads it, winds it and returns it to the magazine,and some guys worry about winding there watch manually.
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Old 2 April 2024, 08:49 AM   #8
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Early chronometer certification

I own a 1960 Rolex 5512 Submariner -It is a 1560 caliber chronometer.

Since the COSC was formed in 1973-74 for Swiss watch movement certification, what was the certification method that Rolex used for its "officially certified"
or superlative chronometers prior to COSC?

Was it in-house at the Swiss factory or did Rolex out-source the movement testing and certification?
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Old 2 April 2024, 11:29 AM   #9
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Pretty sure that most Chronometer testing was done by the individual manufacturers prior to the Swiss Government deciding that it needed to be consistent and controlled.

Rolex did submit some of their watches for KEW testing, which you can google as the article I wrote about this for the forum seems to have been lost. These tests were mostly for bragging rights and used finely tuned examples.
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Old 2 April 2024, 10:00 PM   #10
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Thanks Larry for the insight. I will look up that KEW testing article.

Been intrigued lately by a 1315 caliber by Blancpain. Their Fifty Fathom collection,
excepting size, are good- tough watches for divers. They did start their dive watches the same as Rolex did about 1953.
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Old 2 April 2024, 10:48 PM   #11
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Before COSC certification, watches were submitted to Swiss "Bureaux Oficiales" BO's
for testing. Hodinkee did an extensive article written by Eric Wind on the KEW observatory 44-day in depth testing procedure.
About 100 were submitted by Rolex for KEW certification and those received a certificate.
They also became quite valuable as collector's interest peaked over rare watches that were extremely accurate.
Originally, the KEW (UK) standard testing was for the British Navy chronometers, requiring accuracy under stringent conditions.
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Old 3 April 2024, 08:12 AM   #12
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Quote:
Originally Posted by SOG DIVER View Post
Before COSC certification, watches were submitted to Swiss "Bureaux Oficiales" BO's
for testing. Hodinkee did an extensive article written by Eric Wind on the KEW observatory 44-day in depth testing procedure.
About 100 were submitted by Rolex for KEW certification and those received a certificate.
They also became quite valuable as collector's interest peaked over rare watches that were extremely accurate.
Originally, the KEW (UK) standard testing was for the British Navy chronometers, requiring accuracy under stringent conditions.
Great info.
Thanks for taking the time and adding that into the mix.
I was completely unaware of this
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Old 3 April 2024, 11:21 AM   #13
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More details of the earlier Swiss and Rolex contributions to accurate pre-COSC
testing and examinations revealed observatories at Neuchatel (18661975)
and Geneva (18731967). The Swiss BO's were in existence between 1877 and 1956
for chronometer testing. In 1910 and 1914, Rolex submitted two separate references for testing and both received certificates as meeting accuracy standards as chronometers.

The Swiss 196173 standard required a mean daily rate in 5 positions of -1/+10 sec daily rate. In 1973, the the BO's came under the Swiss C.O.S.C. which specified a daily rate
in various positions of -4/+6 seconds to be certified as chronometers.

Rolex/Tudor probably submit more watch movements for chronometer certification than any other Swiss watch manufacturer. That also most probably means the most chronometers certified world-wide. Something to reflect on.
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Old 3 April 2024, 07:35 PM   #14
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Rolex/Tudor probably submit more watch movements for chronometer certification than any other Swiss watch manufacturer. That also most probably means the most chronometers certified world-wide. Something to reflect on.
It's not a probability.
It's a fact and has been the case for quite a long time.
It's understandable really, as i think i saw somewhere recently that Rolex make more watches than the other 3(maybe 4) other combined top manufacturers in the world in their own right and keep in mind that all Rolex movements are COSC tested prior to the in-house Superlative Chronometer series of tests.
Basically, it's entirely fair to say that nobody else can ever come close to the crown in that regard.

Of course there is METAS now, so the mix of accurate watch movement testing is rather different.
But the crown is so far out in front that it's not even a race.
It just is what it is and impressive.

Thanks for delving deeper into it
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