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Bremont H-4-Hercules-Rose-Gold New Rose gold 43mm Automatic United States of America, New Jersey, River Edge
TOP
Bremont PREORDER Bremont H-4 HERCULES Rose Gold Limited...
$19,121
Free shipping
Professional dealer
706
US
Bremont Supermarine Bremont RFU 150 New Steel 43mm Automatic United States of America, New Jersey, River Edge
TOP
Bremont S500 RFU 150 Men's LIMITED EDITION Blue Dial Automatic...
$4,995
Free shipping
Professional dealer
706
US
Chopard Grand Prix de Monaco Historique 168569-3001 New Titanium 44mm Automatic United States of America, New York, New York
TOP
Chopard Grand Prix de Monaco Historique 168569-3001 Ti...
$4,545
Professional dealer
917
US
Omega Constellation 14381-2 Very good Yellow gold 35mm Automatic
TOP
Omega Constellation Pie Pan Rail 18K Gold Automatic Automatik...
$12,045
Professional dealer
712
DE
Tudor Black Bay 79230R-0003 Very good Steel 41mm Automatic United States of America, Florida, Hollywood
TOP
Tudor Black Bay Heritage 79230R 41mm Stainless Steel - April...
$3,550
Professional dealer
34
US
Omega Seamaster Diver 300 M 212.30.41.20.03.001 Very good Steel 41mm Automatic United States of America, California, Pasadena
TOP
Omega 41mm Seamaster — Serviced by Omega in August 2021 — Box...
$4,150
Professional dealer
92
US
Rolex Day-Date II 218238 Very good 41mm Automatic United States of America, Texas, Austin
TOP
Rolex : Day-Date II President : 218238 : 18k Gold : champagne...
$47,695
Professional dealer
826
US
Omega Seamaster Planet Ocean 215.30.44.21.01.001 Very good Steel 43.5mm Automatic United States of America, California, Los Angeles
TOP
Omega 2021 Seamaster Planet Ocean 600M 43.5mm Box/Cards...
$5,249
Free shipping
Professional dealer
212
US
Rolex Lady-Datejust 69158 Very good Yellow gold 26mm Automatic United States of America, California, Newport Beach, Orange County, CA
TOP
Rolex Lady-Datejust
$12,595
Free shipping
Professional dealer
76
US
Omega Speedmaster Professional Moonwatch Moonphase 304.30.44.52.01.001 Very good Steel 44mm Automatic United States of America, Illinois
TOP
Omega Speedmaster Moonwatch Moonphase 44mm Chronometer Steel...
$8,150
Professional dealer
19
US
Breitling Navitimer AB01211B1B1A1 New Steel 43mm Automatic United States of America, Kentucky, Lexington
TOP
Breitling Navitimer B01 Chronograph 43 Swissair AB0121
$5,050
Free shipping
Professional dealer
144
US
Rolex Oyster Perpetual 39 114300 Very good Steel 39mm Automatic United States of America, California, Stockton
TOP
Rolex Oyster Perpetual Dark Rhodium (Grey) Dial 39mm 114300
$7,500
Free shipping
Professional dealer
18
US
Rolex Day-Date 40 228239 Very good White gold 40mm Automatic United States of America, Illinois, Springfield
TOP
Rolex Day-Date 40
$46,500
Professional dealer
161
US
Rolex Datejust 126334 New Steel 41mm Automatic United States of America, Florida, Orlando
Rolex 2021 Datejust 41 Blue Index Dial Jubilee NEW 126334...
$14,495
Professional dealer
640
US
Hublot Classic Fusion Aerofusion 525.OX.0180.LR New Rose gold 45mm Automatic United States of America, New York, Brooklyn
Hublot Classic Fusion Aerofusion Chronograph 45mm Rose Gold
$26,950
Professional dealer
 
US
Rolex Sky-Dweller 326934 Unworn Steel 42mm Automatic United States of America, Texas, Austin
TOP
Rolex : Sky-Dweller : 326934 : Stainless Steel : blue dial
$31,150
Professional dealer
826
US
Rolex Datejust 126334 Very good Steel 41mm Automatic United States of America, California, Los Angeles
TOP
Rolex Datejust 41 Rhodium Diamond Fluted Oyster Box/Papers/Car...
$13,499
Free shipping
Professional dealer
212
US
Omega Seamaster Planet Ocean 215.30.44.21.01.001 Very good Steel 43.5mm Automatic United States of America, California, Newport Beach, Orange County, CA
TOP
Omega Seamaster Planet Ocean 600M 43.5mm
$4,795
Free shipping
Professional dealer
76
US
Rolex Submariner Date 126610LN New Steel 41mm Automatic United States of America, Pennsylvania, Philadelphia
Rolex Submariner "Date" 41mm Black Ceramic
$17,995
Professional dealer
12
US
Rolex Sea-Dweller 126600 Unworn Steel 43mm Automatic United States of America, California, Los Angeles
TOP
Rolex 126600 Red Sea-Dweller 43mm 50th Anniversary Steel MK2
$15,900
Professional dealer
123
US
Omega Constellation 168.005 Fair Gold/Steel 34.0mm Automatic United States of America, California, Stockton
TOP
Omega Constellation Cal. 564
$1,636
Free shipping
Professional dealer
18
US
Rolex GMT-Master II 16710T New Steel 40mm Automatic United States of America, Pennsylvania, HARRISBURG
TOP
Rolex GMT-Master II UN-WORN Boxes Papers Pepsi Blue Red Bezel...
$19,378
Free shipping
Professional dealer
190
US
Rolex Submariner Date 126610LN New Steel 41mm Automatic United States of America, Florida, Orlando
Rolex 2021 Submariner Date 126610 LN 41MM NEW
$15,995
Professional dealer
640
US
Ulysse Nardin El Toro / Black Toro 326-00-3 New Rose gold 43mm Automatic United States of America, Florida, Ft lauderdale
Ulysse Nardin El Toro Perpetual
$45,407
Professional dealer
6
US
Rolex Daytona 116500LN Very good Steel 40mm Automatic United States of America, Texas, Austin
TOP
Rolex : Cosmograph Daytona Chronograph: 116500LN : Stainless...
$37,995
Professional dealer
826
US
Rolex Datejust 126334 New White gold 41mm Automatic United States of America, California, Los Angeles
TOP
Rolex Datejust 41 Black Index Fluted Oyster Box/Papers/Card...
$12,999
Free shipping
Professional dealer
212
US
Omega Seamaster Aqua Terra 220.12.43.22.03.001 New Steel 43mm Automatic United States of America, New York, New York
TOP
Omega Seamaster Aqua Terra 150m Master Chronometer Gmt
$8,300
Free shipping
Professional dealer
994
US
Rolex Datejust 126334 Very good Steel 41mm Automatic United States of America, Pennsylvania, Philadelphia
Rolex Datejust 41 Stainless Steel 126334
$12,250
Professional dealer
12
US
Rolex Sea-Dweller 126600 Very good Steel 43mm Automatic United States of America, New York, New York
Rolex Sea-Dweller Steel 43mm Black Dial 126600
$15,999
Free shipping
Professional dealer
133
US
Omega Constellation Day-Date 168.029 Good Gold/Steel 35mm Automatic United States of America, California, Stockton
TOP
Omega Constellation Cal. 751 18K Gold Capped Vintage 1970
$2,400
Free shipping
Professional dealer
18
US
Rolex Datejust 126334 New Steel 41mm Automatic United States of America, New York, New York
Rolex Datejust 41mm Fluted Wimbledon Dial Oyster 126334
$14,230
Free shipping
Professional dealer
469
US
Rolex Sea-Dweller 126600 New Steel 43mm Automatic United States of America, Florida, Orlando
Rolex Sea-Dweller SD43 126600 NEW 50th Anniversary
$15,995
Professional dealer
640
US
Omega Seamaster Aqua Terra 231.10.43.22.01.001 New Steel 43mm Automatic United States of America, Connecticut, Greenwich
Omega Seamaster Aqua Terra Gmt
$6,800
Professional dealer
21
US
Parmigiani Fleurier Toric PFC423-1600201-HA1241 Very good Rose gold 42mm Automatic United States of America, Texas, Austin
TOP
Parmigiani Fleurier : Toric Chronometre Grand : PFC423-1600201...
$15,950
Professional dealer
826
US

Chronometer - Certified Precision

"Chronometer" may sound like a fancy name for a normal watch - after all, it just comes from the Greek words for "time" and "measure" - but chronometers are really something quite special. Chronometers are watches, yes, but watches that have been tried and tested and certified to meet exacting precision standards. The COSC in Switzerland determines which watches may actually call themselves "chronometers".


The Oceanic Origins of Chronometers

Though the Swiss set the standard, the English coined the word. In the quest to calculate the longitude, the Englishman Jeremy Thacker, a clockmaker of extraordinary skill, created a series of increasingly accurate clocks, well beyond what had had previously been achieved. The clocks were intended to be used aboard ships and had to keep absolutely accurate time in order to allow for calculating longitude precisely, and thus fixing the position of the ship in the vast ocean. The last of Thacker's chronometers was actually more like a very large pocket watch.

Other clockmakers - and increasingly watchmakers - copied from and improved upon Thacker's final chronometer, producing watches of greater and greater precision. The original standards for accuracy were actually far more exacting than those currently maintained by the COSC in Switzerland, so very few watches were certified as chronometers and thus very few were actually produced and sold. The original chronometer requirements for mechanical watches are no longer necessary, since digital watches can already exceed them, but chronometers are still manufactured and sold (and resold) today as examples of extremely fine precision engineering. The use of jewels and precious metals in watches owes its origins to chronometers - these materials were used to make the mechanical movements as precise as possible.


Officially Certified Chronometers

Chronometers are no longer rare. More than a million Officially Certified Chronometer certificates are issued each year. Those watches that pass the most rigorous of the COSG's tests are rewarded with a special serial number and, indeed, the right to call themselves "chronometers" at all. Chronometers must meet several requirements: they must display the seconds; they must be highly precise; they must demonstrate that precision over the course of several consecutive days of testing; they must perform precisely in different positions and at different temperatures.


Chronometers in Everyday Use

This may sound extreme, but such reliability was crucial for individuals and groups that had to rely on the precision of portable mechanical timekeepers in the past. Pilots watches, for instance, needed to perform as chronometers (and those that did not had to be hackable). The famous B-Uhren, commissioned by the German Luftwaffe and manufactured by several companies, were chronometer-certified pilots watches - or chronometers that were used as pilots watches, depending on your perspective. Interestingly, despite the many years between Thacker's invention and the production of the B-Uhren, chronometers were still tightly bound to use in navigation.

First at sea, then in the air. And, still today, at sea again - or at least under it. Some diving watches, like the Rolex submariner, are also certified chronometers. Divers must be able to reliably track how long they've been under and how much time they have to surface.

Though their accuracy may have been eclipsed by digital watches, chronometers are still useful today.