Bought a Rolex, can't tell if it's real?

[Kirsty18670]

Hi there. I recently found a Rolex in a charity shop, I don't think the old ladies who worked there realised what it was. It is a Rolex Oyster Perpetual Explorer, could anybody tell me how to identify whether this is real or fake? It has the holographic logo on the back which moves and there is a floating crown. It is quite heavy, and has an etched crown just underneath the 6. The glass is not scratched or marked, and when water is applied it pulls together. It has lots of numbers on it but I'm not sure what is actually supposed to be there. Any information given would be appreciated. Thanks a lot in advance!!