Identifying watch authenticity through letter markings

Many people, including watch repairers, pay little attention to the letter markings on watch bridges. If a watch is from an imported Swiss brand, its movement bridges will certainly feature certain letter markings, which typically include:
　　1. Movement manufacturer (e.g. ETA)
　　2. Movement calibre (e.g. 2824-2)
　　3. Patent marking (PATENTED)
　　4. Jewel count (e.g. 25 JEWELS)
　　5. Country of production (SWISS)
　　6. Unique manufactory hallmark
　　7. High-end watch movements also feature a serial number
　　8. High-end watch movements feature the Geneva Seal
　　9. High-end watch movements also feature markings indicating the testing and certification the watch has undergone (for instance, being tested at three temperatures and in five positions)
　　10. Brand lettering or trademark (usually engraved on the oscillating weight)
　　11. Regulation and precision adjustment markings (usually engraved on the balance bridge)
　　Generally speaking, the more complex and prestigious a watch is, the more markings its movement will have—something that replica watch brands often fail to replicate properly. Therefore, this serves as a reliable method for determining authenticity.
　　Engraving on bridges is typically quite difficult and must be completed before final assembly. It is especially hard to engrave on an oscillating weight; certain materials, such as tungsten alloys (which use metals of high specific gravity), cannot be stamped. Consequently, when counterfeit watches attempt to forge genuine brand markings, they can only create a thin metal sheet, engrave the markings onto it beforehand, and then glue it onto the oscillating weight, though laser printing is also used.
　　I have also seen replica Patek Philippe watches where expense was spared to engrave the movement bridges. However, both the font size and colour were poorly executed; the lettering was excessively large and spaced out, and the tone did not match the style of genuine timepieces.
　　As you know, ETA movements are currently used by various watch brands. Therefore, one cannot simply look at the calibre number to determine whether a watch is genuine. As I mentioned above (point 6), different brand manufactures each have their own distinct markings. For example, ENICAR engraves (or stamps) the letters AR on the main movement bridge, whilst TITONI features the letters PH, which serves as an important basis for us to judge the authenticity of a watch.