Fake watch manufacturers still can't get the proportions right. This is all a matter of degree. Although it is only a few tenths of a millimeter, it is enough to give the impression that there is something wrong with the harmony of the room. It could be the thickness of the luminous paint on the hands or the depth of the dial. Humans have a strong sense of proportion, so the tiniest differences can be surprisingly noticeable..
Generally speaking, counterfeit products result in poor print quality. You may need to use a magnifying glass to really see the difference, but the printing quality of fake watch dial elements is usually softer and less legible than the authentic ones. Look for sharp edges and solid lettering to help confirm it's original..
Don't just use your eyes to judge the authenticity of a watch, but also use your hands. The feel of a watch is sometimes a very clear indicator of small details that a fake can't match. Are the case and bracelet sharp? Does the buckle feel a little too thin when it clicks into place? Does the replica watches seem too light or heavy? Don't forget the crown. A very good way to judge the quality of a movement is to wind it via the crown. You may not be able to see the movement, but if the mainspring looks uneven or lacks smoothness, you'll know something is wrong..
With a purchase like this, the risk is simply not worth it. The best way to spot a fake is to ask an expert. If you are not sure, if you have the slightest doubt about second-hand watches, ask for certification, or go to a Certified Pre-Owned (CPO, in English). If you want to buy a new watch, but not a fake one, buy it in a store.