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what is a chronometer

Watch 101: What is a Chronometer and Why is It Special?

A chronometer watch refers to those with a higher level of accuracy than most. Find out more about what is a chronometer here!
Apr 24, 2024

If you’re getting into the watch collection, sometimes seeing a “chronometer” letter laying on the top surface of your dial makes you wonder. What is a chronometer, anyway?

Derived from the Greek term, a chronometer means a “time measurer”. However, it’s not merely an ordinary time measurer. It’s a fine-tuned watch that has better accuracy compared to the others. Generally, regarding its accuracy, a chronometer is used for determining longitude at sea.

To be approved as a “chronometer”, a watch must pass some qualifications such as mean variation in rates, average daily rate, the greatest variation in rates, temperature-dependent variation in rate, the distinction between rates in vertical and horizontal positions, rate resumption and the largest variation in rates.

In other words, they are watches that have been tested and approved as a “chronometer” possessing an excellent rate of accuracy. So, when we talk about “what is a chronometer”, it refers to some watches that are inclined to have better performance accuracy compared to others. 

We indeed have discussed this topic in our previous article entitled “chronometer vs chronograph”, but here we will talk about it thoroughly – starting from “what is a chronometer” to some recommendations of chronometers you can consider.

A Brief History of Chronometer Watches

If you have a question regarding “what does a chronometer do?”, I suggest you look back to its initial invention history.

To begin with, the invention of a chronometer was provoked by a certain issue that happened in the early 1700s. Specifically, in 1707, there was a terrible shipwreck involving four British ships which was caused by an error navigation system. 

Because of this, the British Parliament offered £20,000 or equivalent to over $5 million dollars today for anyone who was able to find a method for determining the longitude of the sea. This act resulted in accelerating watchmakers’ independent research to address the problem and earn the rich award.

According to history, the term chronometer was first coined by Jeremy Thacker of Beverley, in 1717. This term refers to his invention of a clock ensconced in a vacuum chamber. Later, this term is also used to describe a marine chronometer that was invented by John Harrison in 1730 for celestial navigation and determination of longitude. 

Up to this time, this chronometer has been much upgraded and considered crucial to open-ocean marine or air navigation. 

Read more: Watch 101: What are the Balance Springs for Watches? 

Chronometer Watch Testing

Now you have known about “what is a chronometer”. But, what’s the difference between a chronometer and a watch? Well, it’s simply said that a chronometer is more than a watch. It is a timepiece that has been tested and certified to meet certain precision standards of accuracy as a “chronometer”. 

Discussing “what is a chronometer”, we certainly won’t be far from the COSC (Contrôle Officiel Suisse des Chronomètres)  term. It is a non-profit organization that upholds the Swiss watchmaking industry as a whole. The organization also takes an essential part in the Swiss watchmaking industry because they are responsible for the watch precision and accuracy testing for Switzerland-made timepieces.  

To be accepted for the test, a watch must be Swiss made and the movement must be able to keep time within an average rate of -4/+6 seconds per day. The tests are conducted for at least 15 days long, in 5 positions, and at 3 different temperatures. 

Most watches that are submitted to the COSC and accepted as “chronometer watches” are the type of timepiece with balance spring oscillators. The test refers to their certification of the ISO 3159 standard. 

Chronometer Watches Recommendation

In this guide, we don’t only serve you with some introductory things about “what is a chronometer”, but also some recommendations for chronometer watches. The watches below are easily available, have great value, and have reasonable prices. So, for your consideration, here is the list.

1. Tissot Ballade Powermatic 80 COSC

Just like what is embodied in the name, Tissot Ballade Powermatic 80 COSC is powered by the Swiss automatic movement that enables the mechanism to run. It boasts 80 hours power reserve which is able to continue telling time accurately even if it’s not worn for three days.

With those specifications, I can tell it’s an innovative movement that outperforms the competition, whose movements generally provide one and half days of power reserve.

2. Mido Commander Chronometer

Another recommendation for Chronometer watches is Mido Commander Chronometer. It has an automatic movement that has been chronometer COSC-certified and able to offer up to 80 hours of power reserve. 

For the piece, since it’s adapted from the iconic piece of the modern codes, Mido Commander features the latest Mido logo, graduated dial, and also sapphire beveled glass. 

Read also: Watch Case Back 101: An Appealing Beauty Beyond the Dial 

3.  Rado Coupole Classic Automatic COSC

Capturing the hearts of traditionalists as in Rado’s 60’s watches, Coupole Classic is a snappy dress watch that also would fit any formal affair. To add some distinctive details, Rado adds some elements such as sapphire crystal, ensuring brilliance, legibility, and ultimate protection for the beautiful cream dial. 

With an officially certified chronometer label, Rado Coupole Classic Automatic offers you guaranteed precision in classic style.

4. Longines Record Collection

The next chronometer recommendation is the Longines Record Collection. It’s released as a tribute to their legacy of traditional timekeeping excellence. Proven as a COSC-certified watch, Longiness Record is well-known for its reliable accuracy and remarkable longevity. 

To complete your watch collection, it’s available in four size-40 mm, 38.5mm, 30mm, and 26mm with a variety of different dials. With stainless steel cases and a sapphire display caseback, Longines Record Collection undoubtedly will be your dressy elegant piece of watch. 

5. Oris Artelier Chronometer-Date

In the present days, chronometers are not only restricted to sea navigation, but also for use on land. Thus, if you want to have a classy chronometer to pair with your daily outfit, Oris Artelier Chronometer-Date could be the answer. 

Has been manufacturing fine watches since 1904, Oris is one of a small handful of Swiss watch brands that specifically make mechanical watches. Described by Oris as the bridge between the past and the future, the Artelier Chronometer Date is a chronometer-certified automatic watch with a classy and elegant look that you can consider.

Well, those are all some basic mandatory things to know about “what is a chronometer”. Now, you have known what a chronometer is exactly and jump to the watch conversation without wondering about it. 

Last but not least, to grab more insights about horology, recommendation, and watch reviews, you can directly jump to our Gnomon Blog. Thank you for reading!

You might also like: Closer Look: Ball Engineer III Marvelight Chronometer Ice Blue Ref. NM9026C-S6CJ-IBE – 904L Steel

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