A watch is considered Swiss, according to the Swiss law, if its movement is Swiss, and its movement is cased up in Switzerland, and the manufacturer carries out the final inspection in Switzerland.
A watch movement is considered Swiss if the movement has been assembled in Switzerland, and the movement has been inspected by the manufacturer in Switzerland, and the components of Swiss manufacture account for at least 60 percent (as of January 2017) of the total value, without taking into account the cost of assembly.
If I buy a BMW X5, which is built in South Carolina, am I buying a German SUV or an American SUV? If I buy an American built Honda or Toyota, is it Japanese or American? Fords and Chevys have plenty of foreign made parts. When I buy an Apple iPhone, which is famously "designed in California", but made entirely in China, is it an American phone? With the rise of global manufacturing and parts production, these answers become complicated.
Affordable Swiss brands like Hamilton, Tissot and Glycine have to source parts from places like China to retain their price point. Even Seiko outsources to China and Malaysia to reduce costs on non-JDM watches. Nearly every microbrand owes its existence to China. When you get to higher priced watches such as Omega and Breitling, I become more concerned about how much Swiss is in the watch. Rolex should give me 100% Swiss for their prices, IMO, not to mention every brand priced above that.
The reality is that an entry level luxury brand, such as Ball and others, likely buys cases, bracelets, crystals, dials and hands from China, buys movements from ETA or Sellita, customizes the movements as needed (with perhaps up to 40% of the value of the movement in Chinese parts) and assembles it all, with final calibration and case up, in Switzerland. It wouldn't surprise me if that's true for higher priced luxury brands, such as everything from the Swatch group, Breitling, etc. What about Tudor? Or Rolex? Good questions.