Nomos states on their website that their watches perform with a close approximation to the specs of ISO 3159 standards for chronometers. However later in the same paragraph, they also state that COSC only tests the mechanical movement itself, not the whole watch as it is naturally worn, and many factors can affect the precision of the watch once worn. Factors like how recently it was wound, the position that the watch is in when not worn (at night for example). Even things like temperature can directly impact the accuracy of a exact replica watches. In general, they say that after much rigorous testing for both quality control and performance, they can have an accuracy of one or two minutes per week.
Other German luxury watchmakers such as Glashutte Original use a German third-party testing facility called Wempe to conform with DIN 8319 specs and standards on some of their calibers such as the Glashutte caliber 36. In some ways, these upper-market German brands even exceed COSC’s ISO 3159 standards. Nomo, on the other hand, is a lower market brand than Glashutte Original and A Lange & Sohne and doesn’t employ these labs to test their watches. Most likely this is to keep costs down.
To summarize: NOMOS neither does third-party lab testing nor do they manufacture the cheaper but more accurate quartz calibers. On the other hand, TAG Heuer, (which has many mechanical watches that are COSC certified Chronometers as well as many battery-powered Quartz watches which are about 10 times more accurate than even the most accurate mechanically powered watches) is considered more accurate than NOMOS watches. Full stop.

TAG Heuer is a brand that has been for over a century and a half and has been producing many popular watches for at least a century before NOMOS even came into existence. Nomos Glashutte is a very young company compared to TAG Heuer and produces approximately 20,000 watches per year. To use the name Glashutte in your brand as they do, your watch needs at least 50% of its caliber made in the town of Glashutte which is in the Saxon region of Germany.
Though NOMOS is a hugely popular brand in Germany, and they have made their way into the hearts of many watch aficionados across the pond in North America, TAG Has been popular for significantly longer and has had the time to expand their brand on an international scale in a way that NOMOS hasn’t.
TAG Heuer replica is one of the top 15 most recognizable and valuable brands of Swiss-made watches. They have an estimated brand value of 764 million CHF / swiss francs. They have also expanded their brand by licensing their brand to companies that manufacture eyewear, fashion accessories, and even mobile phones. IN addition to the above, TAG Heuer has placed their brand at the forefront of major events such as Formula 1 Racing and more. The TAG Heuer brand is more established, larger, and more recognizable than Nomos.

TAG Heuer and Nomos are both interesting brands in their own way when it comes to horology. Nomos is one of the few independent watchmakers that can produce up to 95% of its components entirely in-house. This gives them tremendous control over the quality of their production. They produce both manual wind and automatic (self-winding) watches. However, apart from a GMT watch or a World Time watch, they don’t manufacture any high complication watches.
TAG Heuer has relied on 3rd party movements for many years and has used ETA movements in some of their most iconic watches. Recently they have released a few in-house movements. Additionally, they have produced some watches with high complications such as the Carrera Calibre Heuer 02 Tourbillon Chronograph which also happens to be a COSC certified Chronometer.
In the Swiss watchmaking world, precision is measured in seconds per day of deviation. Some of the most precise rolex replica watches have a Chronometer designation issued by a third-party lab known as COSC who provides the testing for a nominal fee. If the watch achieves an accuracy of no more than -4/+6 seconds per day it is considered a very precise watch and will get the Chronometer designation which the watchmaker can display on the watch.
The catch is that you need to be a Swiss watchmaker to even apply. That’s fine and dandy for a Swiss luxury watchmaker such as TAG Heuer which has many watches that are COSC certified. The question is how do you find out how if a German-made watch such as NOMOS Glashutte is highly accurate?