People say that there are a lot of fakes in ancient coins.
Actually, there are far more phony 1916-D dimes and 1877 cents. And it only takes a little experience to spot one, once you know what to look for. So it is with ancients. If you aren't sure, ask the seller to have it authenticated by a recognized expert, such as David Sear. Greek coins could be archaic, classic or Hellenistic.