I go with the old saying ‘if it is too good to be true then it probably is’. Back in the day when I started as a pawnbroker it was really easy to spot a copy – light, spelling incorrect, dials not working etc. Not today! Some are very good. They even have weights in them to give that heaviness to the watch. First google a photo of the watch from an official website of the brand. Check that all the markings & details are exactly the same. Colourings, words, model numbers go over it with a fine tooth comb. In some cases the only way that you can be sure is to take the back off the watch & check the actual workings of the watch. Quality items have quality fixing & may even have their brand stamped on the internal workings of the watch. Seeking out a watchmaker & paying a fee to confirm the watch is an original could save you hundreds & even thousands in the long run.