I would take it to an Authorized Rolex dealer to be honest. Some Rolex, Omega's that have been manufactured in China actually have internals with exactly the same logo,marks and calibre markings. For instance inside the crystal of Rolex's I think 2003-2004 is a very small laser etched Rolex Crown Logo located at the 6:00 position. Rolex started it to thwart counterfeiters.Well guess what...the Chinese knock offs now have that same etched crown!
In this world today, its best to get things authenticated...heck if they can make a fake Ferrari (see the picture below..yeah its fake) they can fake a Rolex really good nowadays!