There are a number of signs that a Rolex might be fake. If the price is very cheap then it is likely to be fake. One can also look for the magnification of the date on the watch which is 2.5 x on a real Rolex and often only 1.5 x on a fake Rolex. One can also tell by dipping the watch in water as all Rolex watches are water tight. If there is any leak inside the watch it is fake.